@Andi7 : I did not say yours loosened or knocking what you did. From years of mounting things on multiple surfaces I found that a nail is only as tight as what it is attached to. Example, you pound the nail into the "mortar" between the bricks, you are pounding into a base of hardened sand. Now after time and moving the nail will hollow out the hole it is in like a file. Eventually the hole gets large enough to let the nail be loose and fall out. By using an expansion type anchor, it works by expanding tight enough to wedge the screw tight in the hole and stay that way.