If you go to the Dreamweaver site definition and click on "Server" and then edit the server set as the testing server. There you will find a server URL setting. You have to make sure that is the correct url that points to a functioning server and the same directory as the root directory also set in that user interface.
Make sure that if you force https:// that the server url has that as well as www. if your site requires that. What I usually do is copy/paste the server URL into a browser and then wait for your site to come up and then copy and paste it back just in case it changed by a server redirect.