error 579 calling a stored procedure

Hi All
I wrote a stored procedure tahat return a rs using EXEC SQL Set Result Sets Array :DsXRate for :I Rows ;
The stored procedure is written in RPGLE and use select SQL to access to Database,
I create the stored with these istructions:

create procedure acg_persdb/scadman
( Tipo char(1), annodo char(4), Numedo char(7),
Societ chaR(2))
DYNAMIC RESULT SETS 1
external name 'ACG_PERSDB/XFTC002'
language rpgle
parameter style db2sql
contains sql
not deterministic ;

Now when i Try to use it from a program VB ADO that runs on client I receive the error SQLcode -579 that means :”SQL read data Not allowed”
If I remove from my stored proc the SELECT SQL and use SETLL and READ the stored works fine.
Any suggestions about this?

Thanks in advance

Mario