Help with Bullet ricochet!

programming flash
1

[COLOR=#000000][FONT=verdana]Ok i made a tank that can move and shoot but i want the bullet to bounce or “ricochet” off the walls so i gave it a shot but… the bullet bounces off the wall but after i shoot a couple they all suddenly are in sync [/FONT][/COLOR][COLOR=#000000][FONT=verdana] heres my code…
[/FONT][/COLOR][COLOR=#000000][FONT=verdana]


function mouseDown(pEvent){    
if (amo >= 1)    {        
var b = new Bullet();        
b.x = myTank.x;        
b.y = myTank.y;      
  amo -=  1;        
b.angleRadian = Math.atan2(mouseY - myTank.y,mouseX -myTank.x);        b.addEventListener(Event.ENTER_FRAME, bulletEnterFrame);        
addChild(b);    
}}

function bulletEnterFrame(pEvent){       
 var b = pEvent.currentTarget;    
b.x +=  Math.cos(b.angleRadian) * speed;    
b.y +=  Math.sin(b.angleRadian) * speed;    
b.rotation = b.angleRadian * 180 / Math.PI;   
 if (b.y < 0 || b.y > stage.stageHeight)    {       
 speed = speed * -1;        
b.x +=  Math.cos(b.angleRadian) * speed;    
}    
if(b.x < 0 || b.x > stage.stageWidth)    {       
 speed = speed * -1;        
b.rotation = b.rotation * -1;    
}}

[/FONT][/COLOR][COLOR=#000000][FONT=verdana]any help would be appreciated…[/FONT][/COLOR]