Output to U-Mix 44

Hi
I'm set up using some ion Discover DJ MIDI decks through Cross, and i've bought myself a U-Mix 44 soundcard to split my outputs and hear a cue track.
However, after selecting the U-Mix 44 as my sound device, I can only seem to get one channel running at a time, be it cue or master if I use a dual stereo configuration, or track1, or track 2, or cue with external mixer, but they never run simultaneously.
I have a seen a screenshot of a properly configured system which shows Outputs 1,2,3 routing to out1/2, out3/4 and out5/6 respectively. However, I am seemingly only able to select one out as left/right.
I have tried this configuration with both PC and Mac, and am having the same problem. I have tried configuring all kinds of settings outside of Cross to resolve it, but nothing seems to be working.
Please Help!
I'm set up using some ion Discover DJ MIDI decks through Cross, and i've bought myself a U-Mix 44 soundcard to split my outputs and hear a cue track.
However, after selecting the U-Mix 44 as my sound device, I can only seem to get one channel running at a time, be it cue or master if I use a dual stereo configuration, or track1, or track 2, or cue with external mixer, but they never run simultaneously.
I have a seen a screenshot of a properly configured system which shows Outputs 1,2,3 routing to out1/2, out3/4 and out5/6 respectively. However, I am seemingly only able to select one out as left/right.
I have tried this configuration with both PC and Mac, and am having the same problem. I have tried configuring all kinds of settings outside of Cross to resolve it, but nothing seems to be working.
Please Help!