[Zope] Accessing ZClasses other ZClasses via Python

Hi, Can anybody tell me how I can access a ZClass in another ZClass with python? For example I have a ZClass, called "foo_class" that lifes in another ZClass called "Container_class" in a product called "foo_product". So this works fine: "Control_Panel.Products.foo_product.Container_class" But this doesn't work: "Control_Panel.Products.foo_product.Container_class.foo_class" Zope says: Error Type: AttributeError Error Value: foo_class Can anybody help me? ciao, Klaus