Calling variable from nested mc

im trying to use a variable that is on my main timeline from within an mc twice nested but im not sure how to make it work.

on the main timeline i define my variable like so:
var isItemSelected:Boolean;

and inside the mc, i have this:

parent.parent.isItemSelected = true;

which gives me an error : 1119: Access of possibly undefined property isProjectSelected through a reference with static type flash.display:DisplayObjectContainer.

looks like this has been encountered before