My mind was busy, so unfortunally I didnt pay enough attention to everything what PigLover said, but now I see you're both right.
Took a closer look at the order of the cables in the adapter-cable, and sure enough the order is different from the connector to the fan, than the connector to the FCB. It can also be clearly seen in the photo on the eBay-auction I linked to. At first I only looked at the connector to the fan, and it matches 100% to the order on the fan it self. I think I just assumed that it would be the same on the other end.
I guess I need to find some new cables, or find the parts to make my own. Thank you both very much