HELP. Returning REF CURSOR from Oracle Stored Procedure

Hi.  I created a Stored Procedure in Oracle that returns a variable type
REF CURSOR  (it returns a table)

Im trying to execute the SP using a TStoredProc ,  I configured the
parameter to:

datatype:  ftCursor
name : CUR_ESTADO_OUT
ParamType : ptInputOutput

I execute the sp as follows:
StoredProc3.Prepare;
StoredProc3.ExecProc

I also tried with :  StoredProc3.active := True

I'm getting the error:  EDBEngineError 'Operation Not Applicable'
---------------
So I checked the SP and its OK, I execute it normally from a Visual
Basic app.

I'm using  Oracle  8.1.7.2.0
Delphi 6   (enterprise edition. trial version)
BDE :  5.01

Help appreciated. thanks!