[Zope] STORED PROCEDURES

Hi I´m using Zope with an Informix Database conected with ZODBC Product and I need some information about how to call a STORED PROCEDURE I´m trying to call a STORED PROCEDURE that executes a simple query. I do it using a ZSQL method, but when i try to test it, i receive the error message "empty column name". Does anybody have any information about that problem?