EVENT_MOUSE_WHEEL_SCROLL not triggering

I'm trying to enable mouse scrolling on a table control. Simple right? And I could swear I've done it before, but it's not working right now.

int CVICALLBACK TableCallback(int panel, int control, int event, void *callbackData, int eventData1, int eventData2)
{
	switch (event)
	{
		case EVENT_MOUSE_WHEEL_SCROLL:
			DebugPrintf("scroll wheel triggered! type = %i, amount = %i\n", eventData1, eventData2);
			break;
		case EVENT_MOUSE_POINTER_MOVE:
			DebugPrintf("mouse moved! %i, %i\n", eventData1, eventData2);			
			break;
	}
	return 0;
}

The above gets triggers for mouse pointer. I also get triggers for LEFT and RIGHT clicks. But nothing on scrolling. Also tried two different mice. Is this computer related?