TypeError: Error #1009

Hello. I am getting a null object reference error on a button. The button is placed in frame 1 and has small roll over and roll out animations. When the button is clicked, flash resumes play at a point further down the timeline. I can avoid the error by removing the roll out animation or by having the gotoAndPlay command point to a frame earlier than the frame when the button was clicked. How can I change the command to keep the roll out animation and still have the button function as a skip button? Thank you.

AS 3.0 Command:
myBtn.buttonMode = true;
myBtn.addEventListener(MouseEvent.ROLL_OVER,animIn);
myBtn.addEventListener(MouseEvent.ROLL_OUT,animOut);
function animIn(event:MouseEvent):void {
myBtn.gotoAndPlay(5);
}
function animOut(event:MouseEvent):void{
myBtn.gotoAndPlay(11);
}
myBtn.addEventListener(MouseEvent.MOUSE_DOWN,skipintro);
function skipintro(event:MouseEvent):void{
gotoAndPlay(285);
}

Error Displayed:
TypeError: Error #1009: Cannot access a property or method of a null object reference.
at index_fla::MainTimeline/animOut()