The problem is that, instead of pressing the GSX Hotkey ( default CTRL+F12 ), you pressed the key which was used by ParkMe ( CTRL+Shift+P ).
The message is there for a reason: when you press the ParkMe key, likely because you were accustomed to it, your ParkMe function is not "gone" but, instead, it has been integrated by GSX, which does the same thing, just much better, so you should use GSX instead.
Of course, if you change keys using the "Key Assignments" menu under the "Couatl powered menu", those keys might be different and, you should be careful not to assign two functions to the same keys.
