Blinker problems

[cp]

Ok for some reason the left turn signal on my 84 BII wont work with the head lights on. When they're off, it works fine, but as soon as i turn my lights on, it stops working while the right one works all the time. i'm kinda stumped, any thoughts?

 

[rtg143]

Check for grounds. If the left brake light doesn't work with the headlights on, check the rear ground.

 

[cp]

Checked the grounds, and it all looks good. Any thing else maybe?