if you are getting the error "an unidentified error has occurred", then, yes it is the site definition.
PS: James, do I need a root directory in the site definition? 
you may or may not, it depends on the server.
In the files panel, set it to use the testing server. Does this show the site root index.php page? or do you need to go into another directory such as public_html to access the site root index.php page? If you need to go into a subdirectory, then you need to add that as the root directory in the site settings.
Also make sure the web URL is the valid URL for your site, if you enter that URL in the browser, it load the site root index page.
