[Tilecache] Problem with using Tilecache on top of WMS

[Scott Lewis]

I'm just starting to learn TileCache, and I think I have it installed 
correctly.  However, I'm running into a problem when I try to use it.


When I run the following URL directly, I get the map of Greenland that I 
want:

http://nsidc.org/cgi-bin/nsidc_ogc_north.pl?LAYERS=blue_marble_07&
FORMAT=image%2Fjpeg&SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&
STYLES=&EXCEPTIONS=application%2Fvnd.ogc.se_inimage&SRS=EPSG%3A3408&
BBOX=-3000000,-3000000,0,0&WIDTH=256&HEIGHT=256


However, When I try to call my TileCache script, it doesn't.  Here's the 
URL to the TileCache script (note that it's not available externally as 
it's on a development system):

http://DEVELOPMENT_SERVER_NAME/cgi-bin/tilecache/tilecache.cgi?
LAYERS=north_greenland2&FORMAT=image%2Fjpeg&SERVICE=WMS&VERSION=1.1.1&
REQUEST=GetMap&STYLES=&EXCEPTIONS=application%2Fvnd.ogc.se_inimage&
SRS=EPSG%3A3408&BBOX=-3000000,-3000000,0,0&WIDTH=256&HEIGHT=256


Here is the definition in the tilecache.cfg file for [north_greenland]

[north_greenland]
type=WMS
layers=blue_marble_07
url=http://nsidc.org/cgi-bin/nsidc_ogc_north.pl
extension=jpeg
bbox=-3000000,-3000000,0,0


Calling the WMS directly results in the image being created.  The 
TileCache call, however, just generates a blank, blue image.


I looked in the error logs and didn't see anything indicating something 
was amiss there.


Any thoughts or suggestions on what may be the problem?


Scott Lewis
National Snow and Ice Data Center