Book coding doesn't work

1

The coding comes straight from the book (minus my targeted url,and button instance name) How come I keep getting error messages whenever I use coding from the manuals. see example below… Thanks guys

var myUrl:URLRequest = new URLRequest ("…/images/questionpage.swf");
function clickButton(myevent:MouseEvent):void{
navigateToUrl(myUrl);
}
lio_btn.addEventListener(MouseEvent.CLICK, clickButton)

errors:
MouseEvent from the function line can’t be loaded
URLRequest from var line can’t be loaded

note:
whenever I have a
(myevent:______) whatever is in the blank doesn’t load