Button functions not working

hi guys, AS3 has been phenomenal mainly because of it’s new 3D features which i so dearly love. but then i was shocked to see that my simple code doesn’t work anymore.



playagain_btn.onRelease = function() {
	gotoAndPlay("start");
};


it’s giving me this error:

Warning: 1090: Migration issue: The onRelease event handler is not triggered automatically by Flash Player at run time in ActionScript 3.0.  You must first register this handler for the event using addEventListener ( 'click', callback_handler).

i’m not a programmer and for the past years, i have lived with simple coding. what is wrong with this anyway? i hope you can pud some light to this situation im in

thanks