[Zope] Import classes in External method

Hi, How to import classes in an External method? I mean, where to place the module where my class is defined. I tried to put it in "lib/python/" or "Zope-2-2-0/lib/python/Shared", or in "/usr/lib/python1.5/" but I always got the same message : The errror ======= Error Type: SystemError</STRONG><BR> Error Value: Failed to import class myclass from module __main__ mycode ====== import module_of_class def useClass(self): foo = module_of_class.myclass() Bye, FR.