Helllo,
1 - Did the files (an alos the xml file) you want to stream are on same server as the player ? i not you have to put a crossdomain file at the webroot of the server where the files are stored.
2 - This can be also an error inside the xml file, a character missing or a meta not closed correctly for e.g...
check it directly with FF the xml file
3 - if it still not good can you provide me a link ?