three.js adding spotlight to the scene at later time

Question

if I add spotlight to the scene first, all is good, but if I add it to the scene at later time, after all models are loaded, it doesn't appear. Is that bug in three.js or not supported or I need some kind of refresh...

var lighty = new THREE.SpotLight();
lighty.position.set( 90, 54, 70);
lighty.target.position.set( 90, 0, 70);
scene.add(lighty);