SoundChannel not found?

I’m trying to use the SoundChannel class in a project, but it is not recognized.

If I try:


import flash.media.SoundChannel;
...
var _sc:SoundChannel;

I get this error: The class or interface ‘SoundChannel’ could not be loaded.

Even with just the import statement I get the error. SoundChannel lights up like a keyword too. Why can’t I use this class? Thanks.