actionscript-3 - As3 - full screen interactive after NetConnection.call

Question

I've this as3 code that from the Wowza server activates a function and returns a string. But once I get it, I can't go in Full Screen Interactive mode.

this.NetConnectionData.call("isUserPaid",new Responder(function(data:Object):void {
    var val:String=data.isUserPaid+"";
    if(val == "true") {
           this.stage.displayState = StageDisplayState.FULL_SCREEN_INTERACTIVE;
    } else {
            Alert.show("Error!");
    }

}),nomeUser);

And btw, in Html part I've already set "params.allowfullscreeninteractive = true;"

It's a bug or have I done something wrong? Thank you in advance!