How can I shoot at enemies while facing left and right?

Hello. I been trying to have my character to fire spheres at enemies in a 2d platform game. I only can fire the spheres at the right direction. Can someone help me why is it happening, and how to solve it?

 enter code herevar prefabBullet:Rigidbody;
 var shootForce:float;
 var shootPosition:Transform;
 
 function Update()
 {
         if(Input.GetKey(KeyCode.S))
         {
         var instanceBullet = Instantiate(prefabBullet, transform.position, shootPosition.rotation);
         instanceBullet.rigidbody.AddForce(shootPosition.right * shootForce);
         Destroy(instanceBullet,2);
         }
         instanceBullet.velocity = transform.TransformDirection (Vector3.right * 10);
         }