Tween class question? please help

hi, i am having trouble using the tween class.
i’ve set up 2 pointers to mc’s - temp and prevTemp… i would like the tween to update the _x position based on the new value of “prevTemp._x + prevTemp._width,” but it seems that it grabs the initial value, and doesn’t update as the mc properties are changing. is this a shortcoming of the tween class, or am i completely missing out on something? any help would be greatly appreciated. thanks! (code below)

var temp = eval(“s” + i);
var prevTemp = eval(“s” + (i-1));
var tween:Tween = new Tween(temp,"_x",Regular.easeOut,temp._x,prevTemp._x + prevTemp._width,35,false);