Why do nails come out?

[imported_Benno]

Yes. Why is it that some nails don't settle where they are? Here is a nail in wooden paneling on the ceiling that is coming out after being there for over 20 years. It can't be moved with fingers.

 

[nimhed]

I believe more that the panel has not been flush against the glesen.
Now the panel has dried a bit and moved.

 

[jonaserik]

Pin nail with a small head to go in and disappear. Likely also of the electro-galvanized and shiny type, they don't hold well, they tend to creep out. They should be hot-dip galvanized, they are knobby and grip well, and do not tend to creep out.