ListBox issue
 

I placed a ListBox control on a spreadsheet and, for some reason, am having a
great deal of trouble with it. The majority of the time, nothing happens
when I click it - the scrollbar won't work and I can't select anything.
Sometimes, if I turn Design Mode on, then off, it will start working, but not
always. The sheet it's on is not protected. I've tried it with the control
locked and not locked and it doesn't seem to make a difference. What have I
done wrong?