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