Black images for classifieds plugin

I have tried this in different browsers and I can't seem to get the crop function to work. After I upload an image it won't let me crop the image. After I hit the crop buton all I get is a black image. I upload different size images and nothing changes. I checked my /wp-content/classifieds-images directory to see if it is set to 777. All the images inside are just black.
Help.