ButtonThrower: Events for Mouse Up, but not Mouse Down?

I’m attempting to use ButtonThrower to detect button-presses–both keyboard and mouse–and have encountered a problem: while the events seem to fire as expected for the keyboard, I only seem to get mouse-up events, with no corresponding mouse-down events, from the mouse.

I’m using “setButtonDownEvent” and “setButtonUpEvent” to register the relevant callbacks. One thing that might be worth noting is that I’m using the ButtonThrower found by calling base.buttonThrowers[0].node(); this is done at startup (during initialisation of the class that I’m working on), and the ButtonThrower object stored in a class variable. The callback methods mentioned above are only registered later during the program’s run.

What might be going wrong?