checkPolicyFile flag?

I wrote a slideshow actionscript fla that downloads images from picasa and maipulates them as Bitmaps. It works when I test the movie, but if I publish to the web, I get security errors and no images load. I found some help and added

Security.loadPolicyFile("http://photos.googleapis.com/data/crossdomain.xml");

to the top of my fla file and changed the begining part of the picasa RSS URL to match.

I still get another error though:

SecurityError: Error #2122: Security sandbox violation: Loader.content: my.swf cannot access http://lh4.ggpht.com/_GDD1-IxQDF8/S-18yF8St5I/AAAAAAAAAeY/qr4s4-Y4Bow/CIMG0023.jpg. A policy file is required, but the checkPolicyFile flag was not set when this media was loaded.
at flash.display::Loader/get content()
at xmlImages_random_bitmap6_fla::MainTimeline/resizeAndFrameImage()

I really don't know how to proceed to resolve this.