Actionscript 3 Noob Question

This is question number two for me today.

Using Actionscript 3

Have a button called "breckenridge".  I also have a scene called "breckenridge".

On a keyframe is the following code.

breckenridge.addEventListener(MouseEvent.MOUSE_DOWN, mouseDownHandler40);

function mouseDownHandler40(event:MouseEvent):void {

gotoAndPlay(1, "breckenridge");

}

When I test the movie and I press the "breckenridge" button it takes me to the "breckenridge" scene and stops on the the first frame.

Then I get the following error message

TypeError: Error #1009: Cannot access a property or method of a null object reference.

at key_explore_fla::MainTimeline/frame302()

my main timeline, what I am assuming is my first scene called "aspen", stops at frame 300. What gives?

Okay, I know everyone hates scenes because it causes navigation problems.  However I have this .fla split into sections and I intend to add more stuff to each section in the future.  The easiest way I can think to organize these sections with out having a hodge podge of added stuff jumbled on one time line is to break it into scenes.

Thanks in advance for any help.