Uh... I'm probably missing something, but sounds to me like the Sunpak cord is working? Cut off the PC terminal and install a momentary contact switch (closed when pressed), and there you go?
Are the assorted bands (tip/ring/sleeve/etc) the same on the two you tried? If so, then it is simply matching the Sunpak wiring on another cable. You need to the same ring pattern and then determine which wires do what.
Also, you say jack. Do you mean plug? Usually cords will have plugs and the jack will be mounted on the device. Plug is 'male' and jack is 'female.'