i installed a new circuit in a relatively new homeline panel recently. there were no spaces left so i went to the truck and pulled out a 20/20 tandem breaker to free up a space. the only problem was i couldn't find a spot on the bus bar that would allow for the shorter slot on the breaker. i know that i have installed them in homeline panels before and that some panels only have certain spots you can put them. what am i missing here?