GrblGru "Grbl not found @ COM5" HELP!

I am able to program my Arduino MEGA with IDE, no problem with Grbl 5x. But when I try to connect to the board in GrblGru it says "Grbl not found @ COM5". I can't figure out what the issue is but I think it has something to do with the COM port already in use. I am able to make all this work on my Arduino UNO but not the MEGA.

Any ideas as to why GrblGru can't see the program on my MEGA?

Thanks

may be of help?