We are building an application in Silverlight 2 using WCF for data access. Everything has been going fairly well, but one of the developers on my team came across this error trying to insert some data:
"The remote server returned an error: NotFound"
Now the error seems to suggest that there is something wrong with the service. Binding isn't correct, something wrong with the contract interrface, etc. If you've ever tried to debug a silverlight applicatino, you know you can't attach to it with something like fiddler to see what traffic is being sent across the wire. Very frustrating and significant time was spent looking into the problem. There are several posts on this issue and they all seem to suggest that this is where you need to look.
Turns out it had nothing to do with WCF. The method being invoked by the web service was erroring but the error information itself wasn't being propogated. It was sending this 'NotFound' message.
So if you run across this problem, right some tracing or test cases to ensure the method wrapped by the web service itself works. I beat the developer on my team with a wet noodle for not having tested his method prior to exposing it as a service.