Index: django/db/models/loading.py
===================================================================
--- django/db/models/loading.py	(revision 16481)
+++ django/db/models/loading.py	(working copy)
@@ -147,6 +147,7 @@
                     if mod is None:
                         if emptyOK:
                             return None
+                        raise ImproperlyConfigured("App with label %s hasn't models.py module" % app_label)
                     else:
                         return mod
             raise ImproperlyConfigured("App with label %s could not be found" % app_label)