Silverstone rheostat for two fans

[dreamer.redeeme]

Electrical noob here. I know this isn't really PSU centric, but sort of related. I'm trying to figure out how i can run two fans off one of the stock "rheostats" (which may not be rheostats) that silverstone gives with certain fans. The rheostat hooks right into the fan via a two pin connector. So far i've tried running them parallel, which doesn't work... but will start working if one of the two pin connectors is unplugged. running them in series doesn't work at all. Hooking the rheostat to the actual 12 volt line basically allows the fan to be on or off.

Any ideas? Thx in advance

[dreamer.redeeme]

Ok, so, I found that if i connect one fan normally to the mystery fan control knob and connect the red wire of the second fan control input to the ground of the normally connected fan both are speed-controlled. But that leaves one wire, the second ground (maybe not even a ground, just black?) hanging there. As little as i know about electricity, i do know that input without output isn't a good idea. Can anyone enlighten me?

[dreamer.redeeme]

This is for anyone else using this information: for some reason that one fan was an oddball (great to know now that i've cut, soldered, and sleeved control cables for 4 pairs of fans). For all the others, just run the wires parallel. And no, i didn't have the connectors on backwards, i checked :)