Can some HELP with a SOUND ERROR?

Iam trying to control my sound via AS3.  My code looks like this:

var mysound:Mysound = new Mysound();

addChild (mysound);

var mysound:CustomSoundClass =

new SoundClas();

mysound.play();

I gives me an error code:1151: A conflict exist with definition mysound in namespace internal. I and also the website doesn't function properly like my intro movie doesn't play and then it skips thorough everthing else.

What do I need to do, I found something on the internet that helped me to put the first (var mysound:Mysound......), which cut down 90% of the errors. When I Test Movie my site.