SOme one come help me to solve this question

package com.script {

import flash.display.MovieClip;
import flash.events.KeyboardEvent;
import flash.events.MouseEvent;
import com.weaponsystem.WeaponManager;
import com.weaponsystem.weapons.ProjectileSingle;
import flash.events.Event;


public class Bird1 extends Bird{
	
	
	public function Bird1() {
		 var _weaponManager:WeaponManager;
	

		// add basic event listeners
		stage.addEventListener(Event.ENTER_FRAME, enterFrameHandler);
		stage.addEventListener(MouseEvent.MOUSE_DOWN, onMouseDownHandler);
		stage.addEventListener(MouseEvent.MOUSE_UP, onMouseUpHandler);
		
		// create new instance of WeaponManager, pass a reference to stage
		_weaponManager = new WeaponManager(this);
		
		// create weapons: AbstractWeapon(id_string, weapon_manager_instance, x, y, rotation)
		var singleTurret:ProjectileSingle = new ProjectileSingle("gun 1", _weaponManager, 100, 275, 90); // 1 turret projectile gun


		// add created weapons to weapon manager
		_weaponManager.addWeapon(singleTurret);
	
		
		// add solid objects to WeaponManager


	}
	
	//////////////////////////////////////
	// Event Handlers
	//////////////////////////////////////
	
	/**
	 * Enter Frame handler
	 * @param	event	Uses Event
	 */
	 private function enterFrameHandler(event:Event):void
	{
		[COLOR=#ff0000]_weaponManager.update();[/COLOR]
		


	}
	
	/**
	 * Mouse Down handler
	 * @param	e	Uses MouseEvent
	 */
	 function onMouseDownHandler(event:MouseEvent):void 
	{

[COLOR=#ff0000] _weaponManager.fireWeapons();[/COLOR]
}

	/**
	 * Mouse Up handler
	 * @param	e	Uses MouseEvent
	 */
	 function onMouseUpHandler(event:MouseEvent):void 
	{

[COLOR=#ff0000] _weaponManager.stopWeapons();[/COLOR]
}

	}
}

the part that i highlight is the 1120:acess undefined property…