Problems closing netstream object

I am having trouble closing the netstream object. when i unload a videoclipthe video stream remains open.

Im am fetching the external files like this:

function contactClick(event:MouseEvent=null):void {
nextContent = “contact.swf”;
var content:MovieClip = MovieClip(image.content );
content.gotoAndPlay(“exit”);
content.addEventListener(“exit”, onContentExit);
}

I have encountered this problem before but i mean i solved it by
using: image.unloadAndStop()

But this wont work for me now. Just get this error:

Error #1009: Cannot access a property or method of a null object reference.

Would apretiate any help.

Thank you