traceback of gunicorn

gistfile1.pytb

../gunicorn_virtualenv/bin/gunicorn simulador:server
2011-05-03 19:08:56 [4763] [INFO] Starting gunicorn 0.12.1
2011-05-03 19:08:56 [4763] [INFO] Listening at: http://127.0.0.1:8000 (4763)
2011-05-03 19:08:56 [4763] [INFO] Using worker: sync
2011-05-03 19:08:56 [4764] [INFO] Booting worker with pid: 4764
2011-05-03 19:09:27 [4764] [ERROR] Error handling request
Traceback (most recent call last):
  File "/home/tzicatl/Documentos/Codigo/tesis_gstreamer/gunicorn_virtualenv/lib/python2.7/site-packages/gunicorn-0.12.1-py2.7.egg/gunicorn/workers/sync.py", line 98, in handle_request
    resp.write(item)
  File "/home/tzicatl/Documentos/Codigo/tesis_gstreamer/gunicorn_virtualenv/lib/python2.7/site-packages/gunicorn-0.12.1-py2.7.egg/gunicorn/http/wsgi.py", line 213, in write
    assert isinstance(arg, basestring), "%r is not a string." % arg
AssertionError: <gst.Buffer 0xb6a268b0 of size 66 and data 0x0d0a2d2d> is not a string.
^C2011-05-03 19:09:32 [4764] [INFO] Worker exiting (pid: 4764)
2011-05-03 19:09:32 [4763] [INFO] Handling signal: int
2011-05-03 19:09:32 [4763] [INFO] Shutting down: Master