Unable to generate uml diagrams with docs for django rest framework

epydoc --html --graph classtree  ~/uenv/lib/python2.7/site-packages/rest_framework/generics.py
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------
| In /home/batta/uenv/lib/python2.7/site-packages/rest_framework/generics.py:
| Import failed (but source code parsing was successful).
|     Error: ImportError: No module named settings (line 11)
|   
Warning: No information available for rest_framework.views.APIView's base django.views.generic.View
Warning: Unable to render Graphviz dot graph:
         [Errno 2] No such file or directory

It is generating docs but, I'm unabe to see class diagrams in docs.