Help with upgrading towers in a Tower Defence (Actionscript 3.0)

[Squishinator]

I have a tower defence that i am making, and what i am trying to accomplish is to upgrade the tower selected, but it is only upgrading the last tower built. Here is my upgrading code:

function everything() {
	for (l=0; l<dtn; l++) {
			dartSelected = dartTowerForReal[l];
			dartSelected.addEventListener(FocusEvent.FOCUS_IN,createDartMenu);
			dartSelected.addEventListener(FocusEvent.FOCUS_OUT,removeDartMenu);
			function createDartMenu(e:FocusEvent) {
				menuTitle.text="Dart Tower Lvl1";
				menuUpgradeTo.text="DartTower Lvl2";
				menuGoldCost.text="20";
				upgradeInt=2;
				var newColorTransform=new ColorTransform(1,0,0,1,0,0,0,0);
				upgrade.transform.colorTransform=newColorTransform;
				upgrade.addEventListener(MouseEvent.MOUSE_DOWN,upgradeDart2);
				function upgradeDart2(e:MouseEvent) {
					dartTowerForReal2[dtn2]=new DartTower2  ;
					dartTowerForReal2[dtn2].x=dartSelected.x;
					dartTowerForReal2[dtn2].y=dartSelected.y;
					addChild(dartTowerForReal2[dtn2]);
					dtn2++;
				}
			}
			function removeDartMenu(e:FocusEvent) {
				menuTitle.text="";
				menuUpgradeTo.text="";
				menuGoldCost.text="";
				upgradeInt=1;
				var newColorTransform=new ColorTransform(.4,.4,.4,1,0,0,0,0);
				upgrade.transform.colorTransform=newColorTransform;
			}
		}
	}