I am having trouble validating my xml schema. I get these errors on the schema 113: 18 s4s-elt-invalid-content.1: The content of '#AnonType_user' is invalid. 164: 17 s4s-elt-invalid-content.1: The content of '#AnonType_festival' is invalid. Element 'sequence' is invalid, misplaced, or occurs too often. and becuase of those 2 errors, i am getting loads of the same error. This is becuase the attribute id of the festival tag may be empty becuase there is not data for that festival cvc-datatype-valid.1.2.1: '' is not a valid value for 'integer'. cvc-attribute.3: The value '' of attribute 'id' on element 'festival' is not valid with respect to its type, 'integer'. The lines in the schema causing the problems are <xs:element name="user"> <xs:complexType> <xs:attribute name="id" type="xs:integer"/> <xs:sequence> <xs:element ref="personal"/> <xs:element ref="account"/> </xs:sequence> </xs:complexType> </xs:element> <xs:element name="festival"> <xs:complexType> <xs:attribute name="id" type="xs:integer" user="optional"/> <xs:sequence> <xs:element ref="event"/> <xs:element ref="contact"/> </xs:sequence> </xs:complexType> </xs:element> This is a snippet from my XML file. One user has a festival and the other doesn't <member> <user id="3"> <personal> <name>Skye Saunders</name> <sex>Female</sex> <address1>31 Anns Court</address1> <address2></address2> <city>Cirencester</city> <county>Gloucestershire</county> <postcode>GL7 1JG</postcode> <telephone>01958303514</telephone> <mobile>07260491667</mobile> <email>[email protected]</email> </personal> <account> <username>BigUndecided</username> <password>ea297847f80e046ca24a8621f4068594</password> <userlevel>2</userlevel> <signupdate>2010-03-26T09:23:50</signupdate> </account> </user> <festival id=""> <event> <eventname></eventname> <url></url> <datefrom></datefrom> <dateto></dateto> <location></location> <eventpostcode></eventpostcode> <coords> <lat></lat> <lng></lng> </coords> </event> <contact> <conname></conname> <conaddress1></conaddress1> <conaddress2></conaddress2> <concity></concity> <concounty></concounty> <conpostcode></conpostcode> <contelephone></contelephone> <conmobile></conmobile> <fax></fax> <conemail></conemail> </contact> </festival> </member> <member> <user id="4"> <personal> <name>Connor Lawson</name> <sex>Male</sex> <address1>12 Ash Way</address1> <address2></address2> <city>Swindon</city> <county>Wiltshire</county> <postcode>SN3 6GS</postcode> <telephone>01791928119</telephone> <mobile>07338695664</mobile> <email>[email protected]</email> </personal> <account> <username>iTuneStinker</username> <password>3a1f5fda21a07bfff20c41272bae7192</password> <userlevel>3</userlevel> <signupdate>2010-03-26T09:23:50</signupdate> </account> </user> <festival id="1"> <event> <eventname>Oxford Folk Festival</eventname> <url>http://www.oxfordfolkfestival.com/</url> <datefrom>2010-04-07</datefrom> <dateto>2010-04-09</dateto> <location>Oxford</location> <eventpostcode>OX19BE</eventpostcode> <coords> <lat>51.735640</lat> <lng>-1.276136</lng> </coords> </event> <contact> <conname>Stuart Vincent</conname> <conaddress1>P.O. Box 642</conaddress1> <conaddress2></conaddress2> <concity>Oxford</concity> <concounty>Bedfordshire</concounty> <conpostcode>OX13BY</conpostcode> <contelephone>01865 79073</contelephone> <conmobile></conmobile> <fax></fax> <conemail>[email protected]</conemail> </contact> </festival> </member> This is my schema <?xml version="1.0" encoding="UTF-8"?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified"> <xs:simpleType name="postcode"> <xs:restriction base="xs:string"> <xs:minLength value="6"/> <xs:maxLength value="8"/> </xs:restriction> </xs:simpleType> <xs:simpleType name="telephone"> <xs:restriction base="xs:string"> <xs:minLength value="10"/> <xs:maxLength value="13"/> </xs:restriction> </xs:simpleType> <xs:simpleType name="mobile"> <xs:restriction base="xs:string"> <xs:minLength value="11"/> <xs:maxLength value="11"/> </xs:restriction> </xs:simpleType> <xs:simpleType name="password"> <xs:restriction base="xs:string"> <xs:minLength value="32"/> <xs:maxLength value="32"/> </xs:restriction> </xs:simpleType> <xs:simpleType name="userlevel"> <xs:restriction base="xs:integer"> <xs:enumeration value="1"/> <xs:enumeration value="2"/> <xs:enumeration value="3"/> <xs:enumeration value="4"/> </xs:restriction> </xs:simpleType> <xs:simpleType name="county"> <xs:restriction base="xs:string"> <xs:enumeration value="Bedfordshire"/> <xs:enumeration value="Berkshire"/> <xs:enumeration value="Bristol"/> <xs:enumeration value="Buckinghamshire"/> <xs:enumeration value="Cambridgeshire"/> <xs:enumeration value="Cheshire"/> <xs:enumeration value="Cleveland"/> <xs:enumeration value="Cornwall"/> <xs:enumeration value="Cumberland"/> <xs:enumeration value="Derbyshire"/> <xs:enumeration value="Devon"/> <xs:enumeration value="Dorset"/> <xs:enumeration value="Durham"/> <xs:enumeration value="East Ridings Of Yorkshire"/> <xs:enumeration value="Essex"/> <xs:enumeration value="Gloucestershire"/> <xs:enumeration value="Hampshire"/> <xs:enumeration value="Herefordshire"/> <xs:enumeration value="Hertfordshire"/> <xs:enumeration value="Huntingdonshire"/> <xs:enumeration value="Isle Of Man"/> <xs:enumeration value="Kent"/> <xs:enumeration value="Lancashire"/> <xs:enumeration value="Leicestershire"/> <xs:enumeration value="Lincolnshire"/> <xs:enumeration value="London"/> <xs:enumeration value="Middlesex"/> <xs:enumeration value="Norfolk"/> <xs:enumeration value="North Yorkshire"/> <xs:enumeration value="Northamptonshire"/> <xs:enumeration value="Northumberland"/> <xs:enumeration value="Nottinghamshire"/> <xs:enumeration value="Oxfordshire"/> <xs:enumeration value="Rutland"/> <xs:enumeration value="Shropshire"/> <xs:enumeration value="Somerset"/> <xs:enumeration value="South Yorkshire"/> <xs:enumeration value="Staffordshire"/> <xs:enumeration value="Suffolk"/> <xs:enumeration value="Surrey"/> <xs:enumeration value="Sussex"/> <xs:enumeration value="Tyne and Wear"/> <xs:enumeration value="Warwickshire"/> <xs:enumeration value="West Yorkshire"/> <xs:enumeration value="Westmorland"/> <xs:enumeration value="Wiltshire"/> <xs:enumeration value="Wirral"/> <xs:enumeration value="Worcestershire"/> <xs:enumeration value="Yorkshire"/> </xs:restriction> </xs:simpleType> <xs:element name="folktask"> <xs:complexType> <xs:sequence> <xs:element minOccurs="0" maxOccurs="unbounded" ref="member"/> </xs:sequence> </xs:complexType> </xs:element> <xs:element name="member"> <xs:complexType> <xs:sequence> <xs:element ref="user" minOccurs="0" maxOccurs="unbounded"/> <xs:element ref="festival" minOccurs="0" maxOccurs="unbounded"/> </xs:sequence> </xs:complexType> </xs:element> <xs:element name="user"> <xs:complexType> <xs:attribute name="id" type="xs:integer"/> <xs:sequence> <xs:element ref="personal"/> <xs:element ref="account"/> </xs:sequence> </xs:complexType> </xs:element> <xs:element name="personal"> <xs:complexType> <xs:sequence> <xs:element ref="name"/> <xs:element ref="sex"/> <xs:element ref="address1"/> <xs:element ref="address2"/> <xs:element ref="city"/> <xs:element ref="county"/> <xs:element ref="postcode"/> <xs:element ref="telephone"/> <xs:element ref="mobile"/> <xs:element ref="email"/> </xs:sequence> </xs:complexType> </xs:element> <xs:element name="name" type="xs:string"/> <xs:element name="sex" type="xs:string"/> <xs:element name="address1" type="xs:string"/> <xs:element name="address2" type="xs:string"/> <xs:element name="city" type="xs:string"/> <xs:element name="county" type="xs:string"/> <xs:element name="postcode" type="postcode"/> <xs:element name="telephone" type="telephone"/> <xs:element name="mobile" type="mobile"/> <xs:element name="email" type="xs:string"/> <xs:element name="account"> <xs:complexType> <xs:sequence> <xs:element ref="username"/> <xs:element ref="password"/> <xs:element ref="userlevel"/> <xs:element ref="signupdate"/> </xs:sequence> </xs:complexType> </xs:element> <xs:element name="username" type="xs:string"/> <xs:element name="password" type="password"/> <xs:element name="userlevel" type="userlevel"/> <xs:element name="signupdate" type="xs:dateTime"/> <xs:element name="festival"> <xs:complexType> <xs:attribute name="id" type="xs:integer" user="optional"/> <xs:sequence> <xs:element ref="event"/> <xs:element ref="contact"/> </xs:sequence> </xs:complexType> </xs:element> <xs:element name="event"> <xs:complexType> <xs:sequence> <xs:element ref="eventname"/> <xs:element ref="url"/> <xs:element ref="datefrom"/> <xs:element ref="dateto"/> <xs:element ref="location"/> <xs:element ref="eventpostcode"/> <xs:element ref="coords"/> </xs:sequence> </xs:complexType> </xs:element> <xs:element name="eventname" type="xs:string"/> <xs:element name="url" type="xs:string"/> <xs:element name="datefrom" type="xs:date"/> <xs:element name="dateto" type="xs:date"/> <xs:element name="location" type="xs:string"/> <xs:element name="eventpostcode" type="postcode"/> <xs:element name="coords"> <xs:complexType> <xs:sequence> <xs:element ref="lat"/> <xs:element ref="lng"/> </xs:sequence> </xs:complexType> </xs:element> <xs:element name="lat" type="xs:decimal"/> <xs:element name="lng" type="xs:decimal"/> <xs:element name="contact"> <xs:complexType> <xs:sequence> <xs:element ref="conname"/> <xs:element ref="conaddress1"/> <xs:element ref="conaddress2"/> <xs:element ref="concity"/> <xs:element ref="concounty"/> <xs:element ref="conpostcode"/> <xs:element ref="contelephone"/> <xs:element ref="conmobile"/> <xs:element ref="fax"/> <xs:element ref="conemail"/> </xs:sequence> </xs:complexType> </xs:element> <xs:element name="conname" type="xs:string"/> <xs:element name="conaddress1" type="xs:string"/> <xs:element name="conaddress2" type="xs:string"/> <xs:element name="concity" type="xs:string"/> <xs:element name="concounty" type="xs:string"/> <xs:element name="conpostcode" type="postcode"/> <xs:element name="contelephone" type="telephone"/> <xs:element name="conmobile" type="mobile"/> <xs:element name="fax" type="telephone"/> <xs:element name="conemail" type="xs:string"/> </xs:schema>