Group Membership Connector failed with reason Type System.String is not supported.

20130520,22:33:19,Get all entities from connector failed.,Connector,Warning,"Get all entities from connector Learnology Life Group Membership Connector failed with reason Type System.String is not supported. Duration: 00:00:00.1406160
Error details:
System.NotSupportedException: Type System.String is not supported
at Unify.Repository.EntityExpressionQueryVisitor`3.GetDataUtility(Type valueType)
at Unify.Repository.EntityExpressionQueryVisitor`3.CreateEntityValueValueExpression(Expression valueExpression, Expression parameterExpression)
at Unify.Repository.EntityExpressionQueryVisitor`3.VisitBinary(BinaryExpression b)
at Unify.Framework.ExpressionVisitorBase`11.Visit(Expression exp)
at Unify.Framework.LinqContextConversionExpressionVisitorBase`5.VisitLambda(LambdaExpression lambda)
at Unify.Framework.ExpressionVisitorBase`11.Visit(Expression exp)
at Unify.Framework.ExpressionExpressionVisitorBase.VisitUnary(UnaryExpression u)
at Unify.Framework.ExpressionVisitorBase`11.Visit(Expression exp)
at Unify.Framework.ExpressionExpressionVisitorBase.<VisitExpressionList>b__1(Expression originalExpression)
at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
at System.Linq.Enumerable.ToListTSource(IEnumerable`1 source)
at Unify.Framework.ExpressionExpressionVisitorBase.VisitExpressionList(ReadOnlyCollection`1 original)
at Unify.Framework.LinqContextConversionExpressionVisitorBase`5.VisitMethodCall(MethodCallExpression m)
at Unify.Repository.EntityExpressionQueryVisitor`3.VisitMethodCall(MethodCallExpression m)
at Unify.Framework.ExpressionVisitorBase`11.Visit(Expression exp)
at Unify.Framework.LinqContextConversionExpressionVisitorBase`5.ConvertExpression(Expression partitionExpression)
at Unify.Framework.LinqQueryConversionProvider`5.GetOrderedQuery(Expression businessExpression, IQueryable`1 sourceQueryable, TContext sourceContext)
at Unify.Framework.LinqWhereQuery`5.EvaluateQuery(TContext context)
at Unify.Framework.LinqWhereQuery`5.GetEnumerator()
at System.Linq.Buffer`1..ctor(IEnumerable`1 source)
at System.Linq.Enumerable.ToArrayTSource(IEnumerable`1 source)
at Unify.Connectors.RemoveMembershipsSettings.GetClearedGroupIds(IEntityPartitionUpdatableContext groupEntityRepository, ILifeSiteWCFCommunicator siteWCFCommunicator)
at Unify.Connectors.LifeGroupMembershipConnector.GetConfiguredClearedGroupIds()
at Unify.Connectors.LifeGroupMembershipConnector.<GetAllEntities>d__1.MoveNext()
at Unify.Framework.EnumerableExtensions.<ActionOnFirst>d__1c`1.MoveNext()
at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
at Unify.Framework.ActionOnExceptionEnumerator`1.MoveNext()
at Unify.Framework.EnumerableExtensions.<ActionOnLast>d__16`1.MoveNext()
at Unify.Framework.EnumerableExtensions.<ProduceAutoPages>d__9`1.MoveNext()
at Unify.Framework.Visitor.ThreadsafeVisitorEvaluator`1.Visit()
at Unify.Framework.Visitor.VisitEvaluateOnThreadPoolT(IEnumerable`1 visitCollection, Action`2 visitor, Int32 maxThreads)
at Unify.Framework.RepositoryChangeDetectionWorkerBase.PerformChangeDetection(IEnumerable`1 connectorEntities)
at Unify.Framework.ChangeDetectionImportAllJob.ImportAllChangeProcess()
at Unify.Framework.ChangeDetectionImportAllJob.RunBase()
at Unify.Framework.MutexJobDecorator.Run()
at Unify.Framework.DefinedScopeJobAuditTrailJobDecorator.Run()
at Unify.Framework.AsynchronousJobExecutor.PerformJobCallback(Object state)",Normal