Three.js shadow not as expected - three.js

Question

I'm trying to create a shadow under the cube in this jsfiddle, (code below) but the shadow turns out too big, and I don't think the right shape either. What's causing this shadow, and how can I fix it?
Thanks
var initScene, render,
projector, renderer, scene, ground, light,
camera, box, pointLight;
projector = new THREE.Projector;
scene = new THREE.Scene;
renderer = new THREE.WebGLRenderer({ antialias: true });
renderer.setSize( window.innerWidth, window.innerHeight );
renderer.setClearColorHex(0x000000, 1);
renderer.shadowMapEnabled = true;
renderer.shadowMapSoft = true;
document.body.appendChild( renderer.domElement );
light = new THREE.DirectionalLight( 0xFFFFFF );
light.position.set( 20, 80, 0 );
light.target.position.copy( scene.position );
light.castShadow = true;
light.shadowCameraLeft = -60;
light.shadowCameraTop = -60;
light.shadowCameraRight = 60;
light.shadowCameraBottom = 60;
light.shadowCameraNear = 1;
light.shadowCameraFar = 2000;
light.shadowBias = 10;
light.shadowMapWidth = light.shadowMapHeight = 2040;
light.shadowDarkness = .7;
scene.add( light );
box = new THREE.Mesh(
new THREE.CubeGeometry( 5, 5, 40 ),
new THREE.MeshLambertMaterial({
color: 0xffffff,
opacity: 0.7,
transparent: true,
depthWrite: false
}));
box.position.set( 10, 10, 10 );
box.castShadow = true;
scene.add(box);
ground = new THREE.Mesh(
new THREE.CubeGeometry(1000, 1, 1000),
new THREE.MeshLambertMaterial({
color: 0xffffff,
opacity: 0.3,
transparent: true
}));
ground.receiveShadow = true;
scene.add( ground );
camera = new THREE.PerspectiveCamera(
35, window.innerWidth / window.innerHeight, 1, 1000
);
camera.position.set( 100, 100, 100 );
camera.lookAt( scene.position );
scene.add( camera );
renderer.render( scene, camera );
scene.simulate();

Answer 1

For some reason I cannot go to the fiddle but from what I see your cube is at (10,10,10) with size 5 and your light is at (20,80,0). My first guess is that your light is very close to the cube. Try moving the light to (200,200,0) and see what happens.