Mod wheel not working

I just bought an Akai MPK mini vkII, and everything seems to be working fine except one thing.

Whenever i tu the pitch and mod joystick: the pitch works fine, but the mod seems to be adjusting the K1 knob instead, which means the mod wheel is rendered completely useless. How to i make studio one recognize the mod joystick as a seperate input and not the same input as the knob?