WWW fails in Webplayer but not Standalone

I'm trying to use WWW to get send a GET request to a server, but when the webplayer is published to the live site, it can't connect. I assume there's some sort of security problem, but I can't figure out what it could be. The connection works fine in the editor with the correct security domain emulation, and it works as a standalone build, but not in the webplayer.

• I've added the exact URL of the webplayer to the security settings in Editor Settings, of course.

• List item

• The URL is not relative, it's hard coded.

• The editor is getting data back from the live server that the webplayer should be targeting, not a test server or localhost.

• I can open the php page on the server and see that it's there.

• I have a crossdomain.xml at the root of the server.

• I tried adding a web.config file, but it didn't do anything (and it seemed that was the resolution to the unity file itself not being recognized, so shouldn't have worked anyway)

The error I receive from WWW.error is

 Failed downloading http://example.com/example.php

Anyone used WWW in the webplayer before? What could be going wrong here?