This is the error that I get on my web mapping app
Failed to load resource: the server responded with a status of 404 (Not Found)
http://gis.collincountytx.gov/electionpollingplace/
This is a web server that is hosting the app inside the DMZ requesting the ArcGIS Server (two of them behind a load balance F5) tiles from a different location/server inside the network
...and this is the ArcGIS Server that is hosting the maps
ArcGIS JavaScript API: basemapWM

Thank you
Gabi Voicu