buttons inside movie clip dont work

I have a simple HTML website with 5 buttons one of which, a movie clip, drops down 3 more buttons but the buttons dont always work. I get wierd issues for instance: whether I'm on the mcs page or another page completly the drop down buttons only work when Im on the parent movie clips page. When the buttons do work and you click on the button of the page your on  they only work once then the whole issue repeats itself. Hopefully to clarify here is the code inside of the movie clip that directs the drop down buttons.

stop();

var cdButton:URLRequest= new URLRequest("character desin.html");

cd_btn.addEventListener(MouseEvent.CLICK, cd);

function cd(event:MouseEvent):void

    {

        navigateToURL(cdButton,"_self");

    }       

var caButton:URLRequest= new URLRequest("concept art.html");

ca_btn.addEventListener(MouseEvent.CLICK, ca);

function ca(event:MouseEvent):void

    {

        trace("ca_btn");

        navigateToURL(caButton,"_self");

    }           

var dsButton:URLRequest= new URLRequest("draw sketch.html");

ds_btn.addEventListener(MouseEvent.CLICK, ds);

function ds(event:MouseEvent):void

    {

        trace("ds_btn");

        navigateToURL(dsButton,"_self");

    }