What is the value that you have in your Staging / Servers on your "source" server? You would have entered the URL of your "target" server in the Serer service URL. The format should be:
http://mysite-qa.com as the text in the box
If you have the correct value there, you can try hitting the service directly to see if it resolves. The URL would be mysite-qa.com/CMSPages/Staging/SyncServer.asmx and you should be SyncServer details page.