It looks like a security issue, you need to use a crossdomain policy file.
<?xml version="1.0"?>
<!DOCTYPE cross-domain-policy SYSTEM
"http://www.adobe.com/xml/dtds/cross-domain-policy.dtd">
<cross-domain-policy>
<site-control permitted-cross-domain-policies="master-only"/>
<allow-access-from domain="yourDomainName.com"/>
</cross-domain-policy>
and when loading a Sound , you do this:
private var sound:Sound = new Sound();
private var bufferTime:Number = 1000;// set your bufferTime here
// the second argument sets checkPolicyFile to true
private var context:SoundLoaderContext
= new SoundLoaderContext( bufferTime , true );
//anywhere in your code
//assuming you have defined your URLRequest variable.
sound.load( request , context );