CodingForums.com - Event.observe returns error

Here is my script:

Code:

function init(){

        for(i=0;i<numOrbs;i++){

                Orb[i]=[];

                Orb[i].Img=new Element("img",{id:i, src:"./images/Orb.png", style:"display=none", onMouseover:"GrabOrb(this.id,1)", onMouseout:"GrabOrb(this.id,0)"});

                $("container").insert(Orb[i].Img);

                Orb[i].Img.static=0

                resize();  

                var theta;

                Orb[i].PositionX=Xmax/2;

                Orb[i].PositionY=Ymax/2;

                Orb[i].PositionZ=Zmax*.0001;

                theta=Math.PI*2*Math.random();

                phi=Math.asin(Math.random());

                if(Math.random()>0.5)phi=-phi;

                Orb[i].VelocityX=InitialVelocity*Math.sin(theta)*Math.cos(phi);

                theta=Math.PI*2*Math.random();

                phi=Math.asin(Math.random());

                if(Math.random()>0.5)phi=-phi;

                Orb[i].VelocityY=InitialVelocity*Math.cos(theta)*Math.cos(phi);

                theta=Math.PI*2*Math.random();

                phi=Math.asin(Math.random());

                if(Math.random()>0.5)phi=-phi;

                Orb[i].VelocityZ=InitialVelocity*Math.cos(phi);

                Orb[i].renew=0;

                Event.observe(Orb[i].Img,"mouseover", GrabOrb(i,1));

                Event.observe(Orb[i].Img,"mouseout", GrabOrb(i,0));

                }

        setInterval("collisions()",100);

}



function GrabOrb(ID,value){

                Orb[ID].static=value;

                alert(value);

}

it returns this error:

Message: 'handler' is null or not an object
Line: 4503 (prototype script)
Char: 11
Code: 0
URI: http://127.0.0.1/huduzu/Resources/prototype.js

I have posted the script on my host, and you can see it for yourself at:
http://huduzu.trollnest.com/index.php

Please help! I have been about 16 hrs on this and it is the last step for my "Orbs" widget and then I can get on to page content!