you need to save it a preview, to do this go to preferences and then click on " render a preview when saving" then you'll be able to export it.
It might still refuse to be added to a flash file so try changing the extension by Ctrl+clicking the file the go to "get info" then you'll be able to change the extension, .mp3 is the best. [b]BUT ONLY USE THAT IF IT WON"T ADD THE ORIGINAL FILE