[OpenLayers-Users] what does this error mean?

[Gregor Mosheh]

 > Gregor Mosheh schreef:
 >> What does "couldn't calculate tile index for layer" mean? I can't find
 >> anything in Google...
 >> An error occurred: couldn't calculate tile index for layer imagery
 >> from ([-123.890888, 40.587201, -123.846943, 40.631146999999999])

Bart van den Eijnden (OSGIS) wrote:
> This means your settings in tilecache.cfg differ from the settings in 
> your OpenLayers javascript client code.
> Mostly things like resolutions and maxExtent.

Well, I am stumped. I'm handy with Mapserver, but my primary vocation is 
DBA and sysadmin, so I admit to being out of my usual waters. Is there 
some documentation I can read to get up to speed? I can't find the 
documentation for TileCache (just a readme with vague mention of some 
params) and OpenLayers seems to only have the class documentation which 
is sparse and incomplete, so I'm a bit lost as to my suggested reading...

I've been advised to "check the maxExtent and resolutions" but with no 
documentation...

My map, the broken one:
http://69.59.158.10/openlayers/

The error:
An error occurred: couldn't calculate tile index for layer cities from 
([-123.803009, 40.587181999999999, -123.715118, 40.675072999999998])

My tilecache.cfg:

[cache]
type=DiskCache
base=/maps/cache

[schematic]
debug=false
extension=jpeg
type=WMSLayer
url=http://labs.metacarta.com/wms/vmap0
layers=basic
bbox=-124.15456,40.41142,-123.7844,40.61528

[imagery]
debug=false
extension=jpeg
type=MapServerLayer
mapfile=/maps/wms/wms.map
layers=imagery
bbox=-124.15456,40.41142,-123.7844,40.61528

[highways]
extension=gif
debug=false
type=MapServerLayer
mapfile=/maps/wms/wms.map
layers=highways
bbox=-124.15456,40.41142,-123.7844,40.61528

[cities]
debug=false
extension=gif
type=MapServerLayer
mapfile=/maps/wms/wms.map
layers=cities
bbox=-124.15456,40.41142,-123.7844,40.61528