ViewX asks the server what port to use when the script engine initializes i.e. when a mimic is opened. Each mimic has its own instance of the script engine. If the port is changed on the server, mimics that are currently open on clients will stop working. If the web server is not running (due to port clash with other web services on the server), client side scripting won't work.
Mimic was already open and XML port on server was changed. Trying to run the button again gives the following error. The script contained a call to the server using Server.GetOPCValue.
Error message "Unknown Error 0x80072efd"
XML web server could not be started due to port conflict e.g. IIS was already using port 80 and attempt to read the server using Server.GetOPCValue when the script is called.
Error message "404 Not Found"
Error message "405 Method not allowed"
"Permission Denied" (if another instance of SCX was running on the port instead)
If you have a proxy defined in your IE configuration, ViewX will try to use that to talk to the web server. This may not be what you want and depending on your setup it wont work (usually the Unknown Error message). Add exclusions in IE for the ClearSCADA servers if you need the proxy set up.