Storing in SQL, Procedure call

Hi, I'm using freeradius with freetds and unixodbc. I am having an issue using a procedure call to insert to a Microsoft SQL Server. When I try to use the procedure call 'exec', I see the following errors: radius_xlat: 'exec *** rlm_sql (sql): Reserving sql socket id: 8 query: exec *** rlm_sql_unixodbc: '00000 ' rlm_sql (sql): Couldn't update SQL accounting ALIVE record - 00000 But if I don't use a procedure call and use an insert command in its place, it works just find. radius_xlat: 'INSERT **** rlm_sql (sql): Reserving sql socket id: 3 rlm_sql (sql): Released sql socket id: 3 modcall[accounting]: module "sql" returns ok for request 6 My question is why can't I use a procedure call 'exec'? Thanks!