setInterval Q

1

Hi - I can’t see why this setInterval isn’t working …
basically I want it so a new instance of the same image from the library gets placed on stage at various time intervals at a different alpha level each time … >

var myInterval:Number;
var number:Number = 1000;

function ghosts()
{
    number = (7000) + Math.round(Math.random()*5000);
    var T:Number = 3 + Math.round(Math.random()*4);
    var X:Number = (Math.ceil(Math.random()*Stage.width))+200;
    var Y:Number = (Math.ceil(Math.random()*Stage.height))+200;
    _root.createEmptyMovieClip("ghost",this.getNextHighestDepth());
    ghost.attachMovie("bed","bed",1,{_x:Stage.width/2,_y:Stage.height/2,_xscale:5,_yscale:5,_alpha:50});
}
myInterval = setInterval(this,"ghosts",number);

can anyone help me thanks :()