Scaled image with mode LA is just a black square.

[batlock666]

I have a problem when scaling the attached image. This image has mode LA. When I upload this image in Plone, the scaled versions are all black squares. When I convert the image to mode P and upload that image, the scaled versions are correct. Also, when I do the scaling on the command line, following the same steps, the scaled versions are also correct. Is this a problem with plone.scale or PIL or the image itself?