Loose tail light lens????

[Se7en172]

Today I changed my front and rear lights to silvervisions. Happy days!
After fitting the new bulb to the rear offside tail light, I placed the lens back in it;'s place and tries to screw it back in, I have screwed it in say 3/4 of the way but no matter haw had I turn the lock it will not go any further, the rear offside lens is now loose as a result, any fix to this or any other people experienced the same problem?

 

[H182]

I had this when a wire was in the way between the screw thing and the body, you have to look through the hole in the carpet stuff and see if there's any in the way. The screw felt tight because the wire was trapped between.