unity photon instantiate a ball

How do i instantiate a bullet across the network (please dont ask why) i need to see the ball on all other tanks on the network but using photonnetwork.instantiate dosent work it keeps saying it need 3 arguments but it has 3?

I agree with you on Instantiating bullets over Network. But as Tobias says (I believe that’s his name - one of the creators)

NEVER Instantiate a bullet over the network, EVER EVER EVER.

Do RPC Calls.
Pretty much, RPC Call the bullet, and relay to all the other clients that the bullet was shot from this location and ended in this location.

But if you insist on Instantiating do this then.

PhotonNetwork.Instantiate ("BULLET", Barrel.position, Barrel.rotation, 0);

If you want to RPC Call over the network then do something like this.

if (Input.GetButton ("Fire1") && Time.time > nextFire) { // Press left Mouse Button to fire (FOR NOW SEMI AUTO)
			                   photonView.RPC ("Shooting", PhotonTargets.All, null);
			                   GetComponent<PhotonView> ().RPC ("Shooting", PhotonTargets.All);
			                   Shooting ();

void Shooting(){

CHANGE nextFire to what your Rate Of Fire Variable is.

I Hope this helps!
I wish as well there was more documentation on Photon.