Error 1120 - Correct format for sub-nesting?

I have a slideshow (graphicsshow_mc) within a navigation menu (graphicsmenu_mc) - a movieclip nested in a movieclip.  There are previous / next buttons inside the slideshow that work correctly.

Example:

prev_btn02.addEventListener(MouseEvent.CLICK, navBack02);
function navBack02(event:MouseEvent):void {
    gotoAndStop("deinonychus")
}

The navigation menu acts like chapters for a DVD, and I want one button to always go to the beginning.  I copied the other code, but need it modified to reflect that it appears in the parent.

dino_btn.addEventListener(MouseEvent.CLICK, showStart);
function showStart(event:MouseEvent):void {
    gotoAndStop(graphicsshow_mc.("deinonychus"));
}

The problem is I don't know the correct formatting.  All the tutorials and examples I've found are slightly differen from what I need.  I feel like I've tried all sorts of variations with parenthesis, commas, periods, quotes and just can't get it to work.  Everything is named correctly, and spelling in the code was always copy/pasted to ensure continuity.

I'm new with all this, so if someone could hook me up with the correct format, that would help lessen my headache.

**Error** Symbol 'mc_dropdown', Layer 'actions', Frame 19, Line 3:1120: Access of undefined property dino_btn.

dino_btn.addEventListener(MouseEvent.CLICK, showStart);