PS changes image size by cutting transparent areas.

Hi,

if I save an image as png PS automaticaly cuts of the transparent part to make the image smaler (If  I try to save an completet empty image 64x64 it doesn't even create the file). In my case this is an absolut nightmare since I need the exect image proportions.

I work with Visual Studio on the other monitors, so the chances are high that I hit some kind of wired shortcut to activate this behaviour.