Sounds like the bulb is probably good then.
Does your fixture have a removable/replaceable starter (silver can)? That could need replacing.
Generally I've found T12's to work in most any fixture...95 % of the time.
If that's not it, and you can easily return the T12...get a daylight (which is ~6500K) T8 at a local home improvement or lighting shop. You could even take the fixture in with you to make sure the lamp works in it.