Image Properties in Xcode Inspector Does Not Show Image Size

Question

I am curious why the Xcode properties panel in the right pane does not display the size and resolution for my PNG images when I select an image (viewing the image works very well). Image properties show a “-” (double dash) for each property, as in this screenshot: 1

ps. I am using Xcode 4.3.3 and Lion 10.7.4