b5 gen vw xenons help?

[Dave-B5]

alrite guys ive got myself a set of gen vw xenon headlights, from my mates scrapy up north, but when i went to fot them at lunch one of the main beams wasnt workin so i swaped the bulbs 2 check it wasnt the power pack on the back of the lights, and it wasnt. a fuse had gone so i poped in a new one and tried again but this time the other side wasnt workin! i then put the old lights bakc in with new fuses and they were fine so i can one guses its not a wireing issue and must be to do with the lights them selfs but what?

cheers dave