VRinsight MCP Panel - Key Mapper Problem

I've got a VRinsight MCP Combo Panel and I'm trying to use it with an aircraft that requires the buttons/knobs to be programmed manually. When I try to use the Key Mapper program with it, I'm having problems assigning the function to the buttons/knobs on the panel (auto pilot). For example, when I try to program a button as a Mouse Key to select and assign a function, I select Mouse Key/Enable/Left Button then Set - the mouse pointer turns into a cross, but when I move the mouse to area of the panel (auto pilot) over the button, it changes from a cross back to the regular mouse pointer and nothing happens when I click to program the button. Any ideas?