Bullet is spawning, but with no velocity?

var prefabBullet:Transform;
var shootForce:float;

 function Start() {
     while (true) {
         yield WaitForSeconds(Random.Range(1,3));
         Instantiate(prefabBullet, transform.position, Quaternion.identity);
         prefabBullet.GetComponent.<Rigidbody>().AddForce(transform.forward * shootForce);
     }
 }

The bullet spawns where it should, but it just falls to the ground. Any help would be much appreciated!

It seems that var shootForce doesn’t get instantiated with a value. Give it something, else it won’t work!