Variables not working when strict data typing

programming flash
1

Have the following code that does’t work when angle and speed uses strict data typing. Hope someone can help me understand …

 
init();
function init():Void{
angle = -40; // does't work  if ''var angle:Number = -40;''
speed = 5;   // does't work  if ''var speed:Number = 5;''
ball = attachMovie ("ball", "ball",0);
ball._x = Stage.width / 2;
ball._y = Stage.height / 2;
}
function onEnterFrame():Void{
var radians:Number = angle * Math.PI / 180;
var vx:Number = Math.cos(radians) * speed
var vy:Number = Math.sin(radians) * speed
ball._x += vx;
ball._y += vy;
}