Unable to Reference function from non-parent class

So I am trying to access a variable that is defined within my parent code from a class which has been called from my parent code. I am using this:


TileCode(parent).game_quests.add_quest(0);

to try to access the game_quests variable (which is defined within TileCode). However, for some reason it is not picking that up. It is working for other variables which I have called and ran in a similar fashion.
What could be the cause of this?