Hi all. I just got CS3, and have been playing with HDR. After I combine a number images using the HDR Merge, I save it as a .psd. But then I find that I cannot work with it the way I'm used to. For instance, CS3 won't allow me to add a Curves or a Contrast layer. It won't even allow me to duplicate the layer. What should I be doing, what am I doing wrong?