Error executing Interbase Stored Procedure

We are constantly getting the following DBE error message executing an
Interbase stored procedure :

SQLDA missing or incorrect version, or incorrect number/type of variables.
Process stopped.

The procedure has 5 DOUBLE PRECISION input parameters and 2 DOUBLE
PRECISION ouput parameters.
We are using Delphi 3 and tring to execute the procedure with both a
TstoredProc and TQuery component with the
same negative results.
Using the TQuery component the error is raised at Prepare-time while with
TStoredProc component the error
appears at the ExecProc-time.
Does anyone encountered it before ??. Where is the problem and how can we
get around it ??  

Thanks in advance.

--
Valentino Magri
Omega Data Srl
Str. Padana Sup., 317
20090 Vimodrone (MI) - Italy