U-Mix44 as a standard win sound out. -headphones not working

Hi,
please can smbdy help:
I am trying to use my U-Mix44 as a standard w XP soundcard.
Simply I want to run winamp and here the tracks trough the headphone output on the Umixx44 card.
The LED "output 1" flash when song is played over the winamp, but there is no sound coming to the headphones.
I have read all the pdf documentation and there is no topic touching this problem.
thanx
please can smbdy help:
I am trying to use my U-Mix44 as a standard w XP soundcard.
Simply I want to run winamp and here the tracks trough the headphone output on the Umixx44 card.
The LED "output 1" flash when song is played over the winamp, but there is no sound coming to the headphones.
I have read all the pdf documentation and there is no topic touching this problem.
thanx