How are the side marker lamps fixed?

[torbsim]

Hey everyone, I'm installing Headlamps and Side Markers and I noticed that the Side Marker lamps keep slipping out of the new sockets, have I forgotten something to fix them?

As you can see on the picture.

 

[Rozz]

Push them in and give it a twist to lock in place.

 

[torbsim]

Push them in and give it a twist to lock in place.

I already thought so but didn't want to break or destroy anything. Thank you!