now, i am doing drop down menu which learn form youtube. i try to create the button in the drop down menu. when i click the button to link to other scene, it appear errors. WHY? can anyone help me to solve this problem.


HTML Code:
TypeError: Error #1009: Cannot access a property or method of a null object reference.
	at dropdwonmenu3_fla::MainTimeline/frame64()
	at flash.display::Sprite/constructChildren()
	at flash.display::Sprite()
	at flash.display::MovieClip()
	at dropdwonmenu3_fla::aboutsubmenu_3()
	at flash.display::Sprite/constructChildren()
	at flash.display::Sprite()
	at flash.display::MovieClip()
	at flash.display::MovieClip/gotoAndPlay()
	at dropdwonmenu3_fla::aboutsubmenu_3/fl_ClickToGoToScene_2()