Web Screen Painter is attempting to connect to the non SSL http URL even though Service Desk has been configured to connect to SSL.
Error in WSP states that the webpage cannot be found.
In the NX.env file located at the ROOT installation directory of Service Desk Manager there should be the following option:
If this is set to use an http address then Web Screen Painter will attempt to connect to http.
Change this value to https:// and verify that the correct Service Desk URL is set.
Then recycle Service Desk and launch Web Screen Painter, after logging in, WSP should connect to the SSL URL.