All 4 speakers don't work together

I have a white Diezel (USA made) 4x12 cabinet. It has both 8 ohm mono and 16 ohm stereo inputs on back. The problem is that when I plug into the mono input, only 1 side of the cabinet works. If I use the other 16 ohm jack the opposite side works. I cannot get all four speakers to work simultaneously. The sound from each side is good, nothing lacking. I opened the cabinet to check the connections and they all seem to be solid. Does anybody have any suggestions? They would be greatly appreciated!

Somebody did a mistake soldering the speaker input plate.
A picture of this plate would help.

Peter

Pic definitely would help. Can you plug into both mono inputs and get sound out of all 4 speakers?

Thanks for your replies. I will post a pic when I get home from work today. I have not tried plugging into both sides at the same time, but I will also do that later. Please stay tuned for more info.

It's probably four 8 ohm speakers. If each side is working through the stereo jacks, just not through the mono jack, they are probably wired as two pairs: one pair in series and the other pair in series. Then combined in parallel at the jack. I'd try just reflowing the solder at the jack (just heat the connection with a soldering iron) and see if that fixes it.

OK. You are right, they are 8 ohm speakers, and they are wired in pairs. I was able to simultaneously connect 2 separate amps to each input. Worked and sounded good. Here are pics of the Input jack plate from the back, the top and bottom inside. I did not get to reflow the solder yet. I can try that too. Thanks Again!

The two short wires between the jacks are wrong,
Wire them between the upper 4 pins on both jacks
shown in the last pictures.

The right jack would run then both sides of
the cabinet.

Cheers,
Peter

Peter, it was wired how you described. I think the pic was from a deceiving angle. I re-flowed the solder twice, now it works. I was surprised that it didn't work after the first re-flow. It now measures 8 ohms at the mono output and 16 on the stereo side.
Thank You both for helping me out!! I'm gonna rock out all afternoon!!