How to secure exterior plastic trim separating from wall?

Yours may not be the same, but is it the frame which holds the plastic molding which has come loose? If so, behind that plastic insert are screws, front to back. Maybe a few need to be tightened or a slightly larger screw? With a little silicone into the hole first? I redid both sides of one of mine, put 84 stainless steel screws each side, siliconed each hole first and then put in new trim. Just a thought.