Help I cant use multiple cameras with layers. [Solved]

Hello

I have not tried post processing before so i have no idea what im doing. I Have two cameras, one sees everything expect the gun and one sees only the gun. However when I press play there is only one camera active. Like the different cameras cant form a single picture. I made a short film because its difficult to explain something i dont understand. Heres the link. https://ufile.io/lho8w

I just wondered what settings I should use.

Thanks if someone cares

So I screwed around with the settings and apperantly found a solution. I set the deapth off both cameras to 1. And the camera that only sees the gun i set to Deapth only. I did some other stuff too but i dont know if that made any difference.