[Tilecache] Zero length data returned from layer.

[Tyler Durden]

On a production server I've got:

An error occurred: Zero length data returned from layer.
  File "/usr/lib/python2.4/site-packages/TileCache/Service.py", line
421, in modPythonHandler
    host )
  File "/usr/lib/python2.4/site-packages/TileCache/Service.py", line
405, in dispatchRequest
    return self.renderTile(tile, params.has_key('FORCE'))
  File "/usr/lib/python2.4/site-packages/TileCache/Service.py", line
369, in renderTile
    else: raise Exception("Zero length data returned from layer.")

Any idea why?

Thanks,
Tyler