Pulled up at the lights on Monday night and this Scot yells out the window at me "Yee aint got no fookin teellayt meet"

I said what?

He said "Ya teelayt's fooked meet, I caint see et".

I came to the conclusion my taillight's not workin!  

BUT... it works when I apply brakes...???

Anyone care to tell me what I need to do to fix that?

All answers greatly appreciated in advance.

ps: No disrespect to the Scots, I love 'em and this bloke was only trying to help.  I just thought I'd paint the picture, funny as it was.

Darky

Maybe the taillight has a Darkshine to it?

Ha!

Thanks Kingchops... never thought of that!

I'm new to this caper and never knew there was such a thing as a dual element bulb... and that's the problem!