Only third brake like activating?

[6Pnt0hh]

I was doing some work on my girlfriends 2005 Corolla this weekend (Put her a new deck in and some new headlights to get rid of those fogged up ones) and as we were driving back to her place (in different vehicles), I noticed when she pushes her brake pedal, only her third middle brake light lights up, the other two don't light up (if its day time) and if its night time they stay constant, and the middle lights up (and the side lights don't get brighter like they should). Does anyone know what's going on? I appreciate any help. Trying to get this fixed, she's a bit paranoid about driving it now.

 

[Rinconrolla]

Have you checked your sockets to all the bulbs to see if they have rust or condensation ? Bad sockets will trigger a short in all the wiring . Especially if you were getting moisture in the lens