Error ODBC 999 - accessing DB/400 via Client Access on PB6.5

I have crerated a datawindow based on  a DB2/4000 database.
I have no problem accessing/retrieving/updating data when
runnning application under PB dev. environment.
When I generate an .exe application, I have the following message :
"Select error: An error occured, yet no message was returned by the database
driver".
In the odbc log file i have the following error :
"Error 999 (rc -1) : An error occured..."
Did you experienced such a problem ? Thanks for your help.