The application is on a web server in the DMZ, but ArcGIS server is on server Atlas inside the firewall. We have a crossdomain file in place on Atlas and the application works fine internally, but when you try to view it outside our network, none of the map services show up. We have two other web applications deployed externally that use similar proxy pages to call the services from Atlas. This is my first crack at using the Sample Flex Viewer.
One other thing to note, when the proxy page is in place and referenced in the code, the map services don't display internally either. If I remove the proxy page then they display internally but not externally. Any idea?