I think I could help more if I understood what the overall objective is. Are you trying to get a scalar or table-type value from the procedure? If you are getting a scalar value, use an OUTPUT parameter or the intrinsic RETURNVALUE parameter:

-- Output parameter

DECLARE @OutputParam INT

EXEC proc_GetLastKeyValue @Address, @OutputParam OUTPUT

-- Return Value

DECLARE @r INT

EXEC @r = proc_GetLastKeyValue @Address

Am I anywhere close to what you're asking for?