Can Someone plz Help...?

I Hooked up some neons in my car three color changing neons and a wirelight.. it was all working fine for about a month but now 1 of the neons are starting to not work properly... it works on the straight blue setting fine but if i put it onto the changing or straight pink one it half works like there isn't enough power except the other ones work fine, has anyone got any ideas? i hooked it up to were the ilum for the lights next to the cig lighter.. all insulated and soldered.. so i can't figure out whats wrong.. and they are new so.. Can anyone plz help me?

I'd take it back and get a new one. Maybe wait a couple days though in case somebody else actually knows a better answer.