Good to hear that you solved the issue. Just for posterity (and maybe a future user), let me say that the Enterprise Library 4.1 PDBs can be found on the Enterprise Library 4.1 - October 2008.
Also, I think a good approach in these "strange" type of scenarios would be to to trace the database to see the input and output parameters going over the wire.
--
Randy Levy
Enterprise Library support engineer
entlib.support@live.com