How to use Kmix woth linux backtrack 5 R2?

[db-linux]

i have installed linux backtrack 5 r2 and now want to listen music while i program. but when i luanch the kmix application it loads for a while and then nothing....

Note i am using a sony vaio laptop and when i start backtrack it says the following drivers are missing:
Capture: Ensoniq AudioPCI ENS1371 (ES1371 DAC2/ADC)
Output: Ensoniq AudioPCI ENS1371 (ES1371 DAC2/ADC)

also i cant use the buttons om my keyboard so that i can ajust my screen brightnes or volume... this however isnt the fact with linux mint... So what is wrong and how can i fix it?

Thanks...