I agree with Richard. First check in the SL Builder what do you have in your application (what services and where they come from) and then check what you actually get in the web browser on the client. Maybe there is something wrong with the SL app itself. Test creating a new application with the Builder and try to add an ArcGIS Server service and see if you can reach the server machine at all.
Many thanks Alexey and Richard for the help,I tried the fiddler. Please, have a look on what I got:[ATTACH=CONFIG]24714[/ATTACH]What might this indicate for? The issue that the Silverlight works fine on the host machine but fails to do so on the client. Please, have a look on the screenshot below:[ATTACH=CONFIG]24715[/ATTACH]Also, the service can be accessed from arcgis server manager and arcgis JavaScript API[ATTACH=CONFIG]24716[/ATTACH]
----------------------------------------
Jamal Numan
Geomolg Geoportal for Spatial Information
Ramallah, West Bank, Palestine