Clicktag problem avoiding popup blockers

1

I’m just finishing off my first bannerproject in AS3, but I’m having some issues with the clicktag. The code I’ve used works just fine on all browsers except IE, which blocks the popup window. I’ve figured I’m supposed to use the externalinterface call to work around my IE problems. Something like this…

if (ExternalInterface.available) { ExternalInterface.call("window.open");}

But I can not figure out how, and it’s driving me crazy!!
Could someone please give me an example on how to get it working?
The code I’m using on my movieclip called knappen

 
var paramList:Object = this.root.loaderInfo.parameters;
knappen.addEventListener(MouseEvent.MOUSE_UP, openURL);
function openURL(evtObj:MouseEvent):void {
    var request:URLRequest = new URLRequest(paramList["clickTAG"]);
 
 navigateToURL(request, "_blank");
}