Did a little research! This is your cd player?
http://www.decks.co.uk/image.ashx?p=1/21897.jpg&w=915&h=1206If so I do not knwo what you mean with "MIDI mode". We should stick to the timecode CDs and try to eleminate your problem with that first

Okay, so as I already said I do not own the U-Mix44 and I can just help you with pictures from my U46MK2.
Please go to Options, select the third register card (Audio Interface or something comparable, what you see in the picture is german

), click on configuration and in the upcoming window click on control panel. Then something comparable to the control panel of the U46MK2 that you can see in picture one should appear. Please have a look into the menu if there is something about the sample rate.
As UncleVibes has said it is totally important to select a sample rate of 48kHz because only with this value it works due to a know error.
Report any problem - I am here for you!
Cheers,
Steve
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