NZXT case fan not working

[ComicClown87]

So I started putting my new build pc together yesterday and all went well apart from one of the case fans not spinning.
I moved the back and top case fans to the front and replaced those with the NZXT hue fans. But have noticed one of the case fans not spinning. They are connect together through to a Molex into the psu.
Anyone know what could be the problem?

 

[ComicClown87]

It’s a s340. I don’t get it how the are both connected to the Molex but only one works.
I mean I could just try plugging the one that dosnt work into a spare header on motherboard but don’t really understand why it ain’t working now.

 

[ComicClown87]

Well it has two wires off the fans then into a 3 pin connector each, then there is a 2 into 1 connector, other end of that is a Molex connector that I attached to psu. Don’t the the correct terms for all these wires lol.
U wouldn’t be able to see off pics I’m afraid as it’s a bit of a mess behind there all zip tied together lol.
Anyway I just disconnected the one that didn’t work and plugged it into aio header on motherboard. All good now just runs at full speed.