Hide a symbol programatically

Hi all,

I need to hide a symbol on my main stage dynamically, ie without hardcoding it on the timeline.  So I tried this within an IF ELSE statement:

sym.getComposition().getStage().getSymbol("Box_Symbol").hide();

I also tried this:

sym.getComposition().getStage().getSymbol("Box_Symbol").css({"display","none"});

Clearly these are not working...What am I missing here?

Thanks for your help.