I have created a sample query in sql server to parse data from xml and to display it right now. Although I will be inserting this data in my table but before that I am facing a simple problem.

I want to insert NULL in datetime field ADDED_DATE="NULL" as shown in xml given below. But when I executes this query. It gives me error

Conversion failed when converting datetime from character string.

What mistake am i doing. Please highlight my mistake.

declare @xml varchar(1000)
set @xml= '
<ROOT>
    <TX_MAP FK_GUEST_ID="1"  FK_CATEGORY_ID="2" ATTRIBUTE="Test" DESCRIPTION="TestDesc" IS_ACTIVE="1" ADDED_BY="NULL" ADDED_DATE="NULL" MODIFIED_BY="NULL" MODIFIED_DATE="NULL"></TX_MAP>
    <TX_MAP FK_GUEST_ID="2"  FK_CATEGORY_ID="1" ATTRIBUTE="Test2" DESCRIPTION="TestDesc2" IS_ACTIVE="1" ADDED_BY="NULL" ADDED_DATE="NULL" MODIFIED_BY="NULL" MODIFIED_DATE="NULL"></TX_MAP>
</ROOT> '

declare @handle int
exec sp_xml_preparedocument @handle output, @xml

select * from OPENXML(@handle,'/ROOT/TX_MAP',1)
with 
    (
    FK_GUEST_ID INT
    ,FK_CATEGORY_ID VARCHAR(10)
    ,ATTRIBUTE VARCHAR(100)
    ,[DESCRIPTION] VARCHAR(100)
    ,IS_ACTIVE VARCHAR(10)
    ,ADDED_BY VARCHAR(100)
    ,ADDED_DATE DATETIME NULL
    ,MODIFIED_BY VARCHAR(100)
    ,MODIFIED_DATE DATETIME NULL
    )

I am using Sql Server 2005.