Ok, I'm confused

While things may have worked in your particular mix, it is always best to follow the user manual instructions and best practices, which generally means no mixing of hot and common (black and red).

The 24 port board is set up a little differently than the 12 port.  The shorter screw terminals (Labeled A / closest to the edges) are connected to the Red (+) and the taller terminals (Labeled B / in the center) are connected to the Black (-). 

You can connect red and black on the same side but you have to keep red on the shorter terminals (labeled A) and black on the taller terminals (labeled B).

On the MTH 24 port terminal block, the lower levels are all positive (red), and all the upper raised levels are all negative (black) on BOTH SIDES.  All of the upper & lower ports below red are NOT all positive, likewise all uppers & lowers below the black post are NOT all negative.  If you turn it over, you can see on the bottom the printed circuit board travels from the main red terminal to all 24 lower ports on both sides. Black terminal goes to all 24 upper ports on both sides. 

Thanks guys! I am not confused any more, at least for the time being! I am sure something else will come up! LOL

Back side: 

Twenty four port...………………………………………..Twelve port.