Its got me confused, wired up the tail unit today and when I turn the lights on the tail light doesnt work although press the brake and it lights up!

So its not the bulb, nor connection could be the switch gear I guess but the fronts light up?

Is the switch gear likey to be the offending part?

They are double filament bulbs, tail light sections could be stuffed. Otherwise sounds like wiring issue.

Unlikely switch, more like wiring if just installed.

Does stop lamp or rear lamp come on when brake applied, could be wiring reversed or lamp wrong way round.
They are designed to fit one way only, but will just hold in if fitted wrong, [only 1 pin engages] but may not make good contact.

Should have said It's the tyga tail unit. When pressing the rear brake it lights up, will check the wiring again although had the loom apart recently and checked it all over, repairing a number of bodges.

If the rear stop lamp works then either the tail lamp filament or wire is broken.