headlight assembly issue

I just changed my headlight assembely, i ordered new oem headlights. But after changing the assembly while driving at night they seem to bounce a little i put the originals back and and they do the same thing. everything is screwed in right any ideas or suggestions (2001 grand prix 3.8 n/s gt):cool:

There is a tab on one end that needs to be in a slot, it's on the side close to the grills, check that.

Also, check if it is the bracket that is moving or the headlight housing.

the whole bracket is moving. It is in both slots but now the whol thing will move..

there is actually a tab on each side of the headlight. the assemblies in these year GP's are a bit*h to get seated right. you want to slide the headlight behind the fender first, the tab should seat just right...then you gotta fight to get the tab on the grill side to seat. once you get both tabs in...you should be good. then tighten them down with the screws.