I've upgraded an ASP.Net Web application to the latest build of Fluent NHibernate (1.0.0.636) and the newest version of NHibernate (v2.1.2.4000). I've checked a couple of times that the application is running in Full trust. But I keep getting the following error:

 Security Exception

Description: The application attempted to perform an operation not allowed by the security policy. To grant this application the required permission please contact your system administrator or change the application's trust level in the configuration file.

Exception Details: System.Security.SecurityException: Request for the permission of type 'System.Security.Permissions.ReflectionPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[SecurityException: Request for the permission of type 'System.Security.Permissions.ReflectionPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed.] System.Security.CodeAccessSecurityEngine.Check(Object demand, StackCrawlMark& stackMark, Boolean isPermSet) +0 System.Security.CodeAccessPermission.Demand() +54 System.Reflection.Emit.DynamicMethod.PerformSecurityCheck(Type owner, StackCrawlMark& stackMark, Boolean skipVisibility) +269 System.Reflection.Emit.DynamicMethod..ctor(String name, Type returnType, Type[] parameterTypes, Type owner, Boolean skipVisibility) +81 NHibernate.Bytecode.Lightweight.ReflectionOptimizer.CreateDynamicMethod(Type returnType, Type[] argumentTypes) +165 NHibernate.Bytecode.Lightweight.ReflectionOptimizer.GenerateGetPropertyValuesMethod(IGetter[] getters) +383 NHibernate.Bytecode.Lightweight.ReflectionOptimizer..ctor(Type mappedType, IGetter[] getters, ISetter[] setters) +108 NHibernate.Bytecode.Lightweight.BytecodeProviderImpl.GetReflectionOptimizer(Type mappedClass, IGetter[] getters, ISetter[] setters) +52 NHibernate.Tuple.Component.PocoComponentTuplizer..ctor(Component component) +231 NHibernate.Tuple.Component.ComponentEntityModeToTuplizerMapping..ctor(Component component) +420 NHibernate.Tuple.Component.ComponentMetamodel..ctor(Component component) +402 NHibernate.Mapping.Component.BuildType() +38 NHibernate.Mapping.Component.get_Type() +32 NHibernate.Mapping.SimpleValue.IsValid(IMapping mapping) +39 NHibernate.Mapping.RootClass.Validate(IMapping mapping) +61 NHibernate.Cfg.Configuration.ValidateEntities() +220 NHibernate.Cfg.Configuration.Validate() +16 NHibernate.Cfg.Configuration.BuildSessionFactory() +39 FluentNHibernate.Cfg.FluentConfiguration.BuildSessionFactory() in d:\Builds\FluentNH\src\FluentNHibernate\Cfg\FluentConfiguration.cs:93

Anyone had a similar error? I've seach the web / stackoverflow / NHibernate forums but only found people who had a problem when running in medium trust mode, not full trust. I've been developing for several months on this application on this machine with previous versions of Fluent NHibernate and NHibernate.

The machine I'm running this on is 64-bit, you never know that this is relevant.