Yeah yeah yeah, my answer was "strictly" off thread, we have conventions to keep a very complicated existance as simple as possible, yer know, the KISS principle, and I don't...

sp_ is System Procedure not stored procedure, read BOL Newbie

Read BOL about deterministic functions. The root of the question is in non-deterministic functions not being allowed in the body of user-defined functions and an sp is purposely non-deterministic....

Thanks Tim, the "Client Tools Only" approach worked for me.