U-Mix 44

I bought the U-Mix 44 from Mixvibes . When connected to the USB port on the computer , the USB LED on the unit is working . When I play music , the output 1 LED is working , but I hear nothing through headphone .
This problem occurs with Microsoft Media Player , with Cross DJ LE 1.5.2. and also the Cross DJ 1.7.1. I have also I-Tunes , but when the U-Mix44 is connected and selected as master device , i-Tunes stops working and I have to shut it down .
With Cross DJ and the Cross DJ LE , when I try to select in the preferencies the U-Mix 44 as master device , I always get an error message : Error while opening Sound device Mixvibes U-Mix . Error opning primary sound program : BAD FORMAT .
I went to the forum , downloaded the latest updates , but still nothing works .
Everything is working normaly , when the U-Mix is disconnected .
Could somebody give me some advise , please ,
This problem occurs with Microsoft Media Player , with Cross DJ LE 1.5.2. and also the Cross DJ 1.7.1. I have also I-Tunes , but when the U-Mix44 is connected and selected as master device , i-Tunes stops working and I have to shut it down .
With Cross DJ and the Cross DJ LE , when I try to select in the preferencies the U-Mix 44 as master device , I always get an error message : Error while opening Sound device Mixvibes U-Mix . Error opning primary sound program : BAD FORMAT .
I went to the forum , downloaded the latest updates , but still nothing works .
Everything is working normaly , when the U-Mix is disconnected .
Could somebody give me some advise , please ,