Cubase not recognising Audio Input from Analog Mixer

[cubasestudiokid]

Hi ,
I'm plugging my guitar through a Mackie Vlz Pro mixer which has the main out connected to inputs on an M-Audio 10/10 lt. I can hear the sound through my monitors and can play Amplitude no problem but Cubase Studio doesn't seem to pick the sound up.
When I plug a basic preamp in through the XLR input it picks the sound up ok in cubase..
I'm confused as to why this is happening and hope that someone can help!

Thanks

[tacman7]

Test:

Mute the guitar input sound from the soundcard mixer software. The signal should still be going into cubase(if you have it setup right). Then on the audio track you have setup to record the guitar push the orange monitor button. You should hear the guitar now, if you have the tracks output set to the main outs. If that works then it will record.