USB Mixer channel mapping in Cubase 5

I feel stupid asking this question - but here goes anyway

I have a small home studio and i just installed Cubase 5 connected to a Berhringer XENYX X1222USB mixer with 16-Input 2/2-Bus Mixer.

I can’t map input 1(Mixer) to Audio1 (Cubse) without having all the other mixer inputs bleeding into Audio1.
l have read the manual, watched the tutorial CD, and looked in forums and still can’t work out what l have done wrong.

Any assistance would be greatly apppreciated.

Cheers,
Argus.

Solved…Upgraded fron XP to Windows 7 Pro and it works fine