Ah. A lesson from somebody who's built hardware that I'm sure you've now learned: make sure connectors can't plug into eachother unless they're supposed to. Even if they're different connectors, different keying, whatever, sometimes they can still be forced together.
>>Neywin+(OP)
I built a lot of Ikea last month. And I was just marveling how cleverly designed everything was so that it was quite difficult to put two wrong pieces together. Mostly, the only warnings in the manuals were to rotate a piece correctly.