FX.move exception

I am am new to Mootools. I have been tring to move a div section with the following code:

try {
var mover = new Fx.Move($('setPositionTarget'), {
relativeTo: $('chart_div'),
position: 'upperRight',
edge: 'upperLeft',
offset: { x: 10, y: 100 }
});
mover.start(); //moves to the new location
}
catch (e) {
alert(e.message);
}

The start function throws an exception: Object doesn't support this property or method

What am I doing wrong?

did you include all needed stuff from more?

seems like this class is missing?