strange behavior of alert message JSFL Actionscript

I have an SWF extension panel and the issue appears when I try to show an alert if the user selects another document in Animate. It shows many many times, and I can't figure out why..
jsfl code:

var docChangedID = fl.addEventListener( "documentChanged", onDocumentChangedHandler );
function onDocumentChangedHandler(){
     var panelChange = fl.getSwfPanel("mySWFpanel", false );
	panelChange.call( "changeDoc" );
}

 AS code:

ExternalInterface.addCallback('changeDoc', this.enabledList );
function enabledList() : void {	
		list.dataProvider.removeAll();
	MMExecute("fl.trace(\"you are change FLA file\");");
	MMExecute('alert("you are change FLA file");');
	//MMExecute('fl.runScript(fl.configURI + "/WindowSWF/mySWFpanel.jsfl", "showAlert");');
}