380T Case Fans Constantly at Max Speed

[halleyscomet]

Hello Corsair community.

I have a 380T case, that I have recently put back together.

Everything is going well in my build, except the fan control via the fan control button.

I have plugged the rear and front case fans into the fan 4pin headers, and the sata power cable to my power supply. The rear fan and the front fan light up, and spin.

However, pushing the fan control button on the front of the case does nothing and in fact if I hold the fan control button down, the fans slow down and eventually stop! Even the leds go out when pushing the fan control button.

Is there some fundamental misunderstanding of the case fan headers that I have?
Thank you for your time.