Cannot click on menus

I have a USB tablet connected to my computer (I use it for drawing and it's basically a tablet with a pen & special mouse that goes with it, effectively replacing my computer's touchpad). I found I can't use it to click on any menus or the lefthand menu in musescore, i've discovered, but my touchpad works. Am I stuck using the touchpad (not my favorite)? I've never had a problem with any other program not registering my clicks using the tablet.