Thanks for your reply, we've found the problem.
In de .rdlc files the following line exists:
<Field Name="Fields">
<DataField>Fields</DataField>
<rd:TypeName>SD.LLBLGen.Pro.ORMSupportClasses.IEntityFields</rd:TypeName>
</Field>
which caused the problem. In early versions of LLBLGen it worked, but these fields didn't be on the report, so we remove these ones.