Tripod quick release plate

[Bukitimah]

Hi, I don't seem to be able to fasten my tripod quick release plate onto my camera body to prevent it from rotating. No matter how tight I tighten it, whenever the weight of my camera (together with the lens) tilts a certain direction, it got loosen.

I don't seem to experience this previously. Is something I need to do to tighten it? there is only a single screw to hold the plate to the body. Is this normal?