Delete PersonInORG Script

Hello I want to delete the assignments to PersonInOrg. Unfortunately that doesn't work and I don't get a meaningful error. Do I have to do a deep delete?

'Remove all Assigments to all Project Rolls for the user
'==================================================

'Loop throu all sub Project Rols
For Each colbRoleElement As IEntity In colbRole
	Dim colbeAssigments As IEntityCollection
	Dim fRoleAssigments As ISqlFormatter = Session.SqlFormatter
	'Query is there an Assigments to Role and Userid
	Dim qRoleAssigments = Query.From("PersonInORG") _
              .Where(fRoleAssigments.AndRelation(fRoleAssigments.Comparison("UID_ORG", colbRoleElement.GetValue("UID_Org").String, ValType.String, CompareOperator.Equal),fRoleAssigments.Comparison("UID_Person", userUid, ValType.String, CompareOperator.Equal))) _
              .Select("UID_Person", "UID_Org")
	colbeAssigments = Session.Source.GetCollection(qRoleAssigments)
	
	'If Query has Data
	If( colbeAssigments.Count = 1)
		Using uow = Session.StartUnitOfWork()
			For Each assigment As IEntity In colbeAssigments
				assigment.MarkForDeletion()
				uow.Put(assigment)
			Next
			uow.Commit()
    	End Using
				
	End If		
Next