UR28M: routing issue with MIX1, MIX2, ...

Hi all,
this is my first post, sorry if something is wrong.

I just received a UR28M, that I use with my MBP (El Capitan).
I think I have a routing issue: when I play a song from my DAW or youtube or whatever, I see in the DSPMixFx the DAW meter is moving, but JUST for MIX1 tab.
If I switch to MIX2 or MIX3 I see the meter but it’s turned off, no matter the fader position, it seems it doesn’t receive anything. Maybe I’m doing something wrong with the routing?

My purpose is (if there’s a better way to do this, please let me know!)
MIX1: what I’m sending to my main monitor in the control room
MIX2: send to phones 2, creating a mix for say a singer in live room

Thanks in advance for all you support!