I always uploaded it through the mysecondlife website. It tells me once its uploaded. I did try dragging it from my inventory onto the profile pic and it does seem to work. It shows only me the new size which is 512x512, but people still see my old 256x256. Once i log out and then back in it still shows my old one. I think dragging it on shows a preview. I have apply now checked then i click ok, but it doesnt work.