I got a cheap Behringer UCA202 to use as an audio interface to hook directly into my computer from my guitar. Setup would be: Guitar--->U-Control--->Computer(using Amplitube2), many other audio interfaces say they work without a mixer, but I don't get any sound out of this when I use it, am I connecting it wrong or do I need a mixer? It doesn't say anywhere on the website or on MusiciansFriend that I need one. Does anyone own a USB audio interface and could possibly help me...?

...also could I connect my guitar to my Digitech RP-50 and then into the interface and then into the comp, because that works without the interface?
Epiphone LP
Johnson Strat Copy(first guitar)
Epiphone Dr 150 Acoustic
Vox Valvetronix AD30VT
Digitech Jimi Hendrix Experiance pedal
Boss DS-1 Distortion
Digitech RP50
ElectroHarmonix Metal Muff