I set up a TileStache server on Redhat, installing Mapnik 2.2 from source. However, Tilestache is giving me the following error:

```
Traceback (most recent call last):
  File "/usr/lib64/python2.6/site-packages/gevent/pywsgi.py", line 508, in handle_one_response
    self.run_application()
  File "/usr/lib64/python2.6/site-packages/gevent/pywsgi.py", line 494, in run_application
    self.result = self.application(self.environ, self.start_response)
  File "/usr/lib/python2.6/site-packages/TileStache/__init__.py", line 381, in __call__
    status_code, headers, content = requestHandler2(self.config, path_info, query_string, script_name)
  File "/usr/lib/python2.6/site-packages/TileStache/__init__.py", line 254, in requestHandler2
    status_code, headers, content = layer.getTileResponse(coord, extension)
  File "/usr/lib/python2.6/site-packages/TileStache/Core.py", line 414, in getTileResponse
    tile = self.render(coord, format)
  File "/usr/lib/python2.6/site-packages/TileStache/Core.py", line 500, in render
    tile = provider.renderTile(width, height, srs, coord)
  File "/usr/lib/python2.6/site-packages/TileStache/Goodies/Providers/MapnikGrid.py", line 72, in renderTile
    self.mapnik = mapnik.Map(0, 0)
NameError: global name 'mapnik' is not defined

```

**Relevant Information:**

* Other posts have suggested changing 'import mapnik' to 'import mapnik2 as mapnik'. But I got the same error message.
* In other posts originates from TileStace/Mapnik.py, but mine comes from TileStache/Goodies/Providers/MapnikGrid.py.
* Related Post: [Gunicorn fails when using WSGI](https://stackoverflow.com/questions/15724672/gunicorn-fails-when-using-wsgi)

**Question:**

Does anyone know what could be causing this? Thanks in advance!