GroupedNameValueCollectionMissingFieldException when using removeMembership

          <RemoveMemberships>
		  <RemoveMembership groupType="Id" groupValue="{d941e299-0cc0-41cf-83e7-a12100780115}" />
            <!--<RemoveMembership groupType="Name" groupValue="Leavers" siteType="School" laId="100" siteValue="" />-->
          </RemoveMemberships>

20130410,04:39:03,Connector processing success.,Connector Processor,Information,"Processing page 29 for connector Learnology Life Group Membership Connector processed 7775 entities, finding 0 differences. Duration: 00:00:06.6734010",Normal
20130410,04:39:03,Connector Processing started.,Connector Processor,Information,Connector Processing started for connector Learnology Life Group Membership Connector (page 30),Normal
20130410,04:39:04,Get all entities from connector failed.,Connector,Warning,"Get all entities from connector Learnology Life Group Membership Connector failed with reason Exception of type 'Unify.Framework.GroupedNameValueCollectionMissingFieldException' was thrown.. Duration: 00:03:39.2410005
Error details:
Unify.Framework.GroupedNameValueCollectionMissingFieldException: Exception of type 'Unify.Framework.GroupedNameValueCollectionMissingFieldException' was thrown.
   at Unify.Framework.EntityBase`3.GetValue[TValue](TKey key)
   at Unify.Connectors.LifeGroupMembershipConnector.DeleteMembership(ILifeGroupMembershipWCFCommunicator groupMembershipWCFCommunicator, Int32 groupMemberId, Guid groupSiteId, String groupName, IConnectorEntity matchingGroupMembershipEntity)
   at Unify.Connectors.LifeGroupMembershipConnector.DeleteEntities(IEnumerable`1 entityIds)
   at Unify.Connectors.LifeGroupMembershipConnector.<GetAllEntities>d__9.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.VisitEvaluateOnThreadPool[T](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
20130410,04:39:04,Change detection engine import all items failed.,Change detection engine,Warning,"Change detection engine import all items for connector Learnology Life Group Membership Connector failed with reason Exception of type 'Unify.Framework.GroupedNameValueCollectionMissingFieldException' was thrown.. Duration: 00:03:39.3865130
Error details:
Unify.Framework.GroupedNameValueCollectionMissingFieldException: Exception of type 'Unify.Framework.GroupedNameValueCollectionMissingFieldException' was thrown.
   at Unify.Framework.EntityBase`3.GetValue[TValue](TKey key)
   at Unify.Connectors.LifeGroupMembershipConnector.DeleteMembership(ILifeGroupMembershipWCFCommunicator groupMembershipWCFCommunicator, Int32 groupMemberId, Guid groupSiteId, String groupName, IConnectorEntity matchingGroupMembershipEntity)
   at Unify.Connectors.LifeGroupMembershipConnector.DeleteEntities(IEnumerable`1 entityIds)
   at Unify.Connectors.LifeGroupMembershipConnector.<GetAllEntities>d__9.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.VisitEvaluateOnThreadPool[T](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
20130410,04:39:09,Connector processing success.,Connector Processor,Information,"Processing page 30 for connector Learnology Life Group Membership Connector processed 7875 entities, finding 0 differences. Duration: 00:00:06.4517355",Normal