Close all your applications (you may need to use Task Manager to do this) then restart XSplit Gamecaster and your game. Then restart the other applications you need one at a time (you might discover that another application is interfering with XSplit Gamecaster). Closing and restarting is usually enough, but in rare cases a PC reboot may be needed.
If you can use XSplit Gamecaster with other games and only have issues with a particular game then please tell us about it. The “Hello [Username]” drop down menu in XSplit Gamecaster gives you an option to Send feedback, so please use this option to tell us about a particular game you are having trouble with (or if you discover that an application is interfering with XSplit Gamecaster):