Hey veggii... that light fixture sucks. I bought FOUR of them for $23 EACH and all of them ended up with problems- either one or both sides failing within just a couple months of use. Try the El Cheapo ones at Home Depot- the plain white ones- I've found them to be much more reliable.
That's a fixture that takes a T12 or T8 light. You can't run it with a T5. That's a different socket size.