So, I'm attempting to "Generate CSS layers using Illustrator" following the steps documented here: http://livedocs.adobe.com/en_US/Illustrator/13.0/help.html?content=WSC8F4201C-67C8-499c-8B5C-AAED2C055427.html
I've drawn two shapes into a single Layer 1 and used "Save for Web and Devices". AI generates the HTML and the images, but the images are blank or empty files. They have the same dimensions as the two shapes, but no shapes or bitmap data. The files are empty regardless of filetype I choose (png, gif, jpg, etc.)
How can I change this behavior?