simple problem

i have set _global.category = navPaint in a function block

but how do i properly call it in this situation?
the trace works...

_root.navBlank.blank_back.onPress = function() {

trace(category);
var contentTween2:Tween = new Tween (_root.navBlank,"_x",Back.easeOut,14,-150,.5,true);
var contentTween:Tween = new Tween ( category,"_x",Strong.easeOut,-80,14,.5,true);
};

thanks,
anton