针对这个问题，可以直接用文本编辑器打开web工程文件xxx.csproj，找到节点SilverlightApplicationList，修改该值，保存即可
也可以参考：
Not including the xap file from the build, when it is a Team Build will indeed remove the error, but it is not a solution to the problem!The question is: why is the xap file not copied to the clientbin folder when running under TeamBuild.
The magic seems to happen in the WebApplication project, because that one has a reference to the Silverlight application.
In my case I had renamed the Silverlight project and the folder where it lived in.
So the solution is as follows:
Open VS, right-click the web project and select Unload Project, next right-click the web project again and select Edit xxx.csproj.
Locate the <SilverlightApplicationList> tag and edit the path and project name so they are correct again.
Save the file and Check-in the file into TFS.
Restart your Build.