Help Recording a performance on 2 separate tracks

[glitterball]

Hi, I have a problem: I got a macbook pro, novation xiosynth as audio interface(2 inputs , 1 xrl, 1 1/4), and live 8. I have to record a bass line connecting (contemporary):

d.i. from the head (channel 1 with xrl on track 1) and

sm57 on the cab speaker (channel 2 with 1/4 input on track 2)

Ok, I set ext.in respectively on 1 for 1st track, and 2 on the 2nd;they are contemporary armed.

Every track records both d.i. and mic;they're not separate! I've tried to set input config both in mono and stereo but nothing. Anyone can tell me where I'm wrong?