Hi Ben and Giorgio,
Thanks for your response.
I traced the import with Process Monitor and after a lot of trials , i found that the trouble was coming from xerces-c_2_6.dll .
If i copy Xerces-c_2_6.dll from C:\Program Files (x86)\Fichiers Communs\Powersoft Shared to C:\Program Files (x86)\Sybase\Shared\PowerBuilder it works fine.
Gilles