Esc key in Key/Mouse tab

So I have a few programs that use the Esc key to close the window or a prompt.  I used to be able to do that with PowerPro on an older version.  
 

 I tried setting this up recently, and when I choose the Esc key, with or without a modifier key, then the OK button grays out so I can't use it.  I've even tried to replace this with the virtual key, 325, but that doesn't work either.
 

 Is there a way to setup the Esc key to close a window in programs that don't support Esc keys closing the window?