BCE0005: Unknown identifier: 'transform'

I have looked around to find an answer to my problem but have not come across any, so I'm sorry if I did overlook it. My script was working in the previous versions of Unity but ever since I did a recent update (I've been absent for a while) a lot of scripts have errors written all over them. Here is the script...

 //class that defines the physical properties and attributes of the cannonball
 class cannonBlast {
     var cannonball : GameObject;            //create a slot to assign the cannonball prefab to
     var blastParticle : ParticleEmitter;    //create a blast particle slot to assign a particle emitter
     var cannonLight : Light;                //create a light slot to assign a light prefab for when the blast occurs
     var spawnPos : Transform;                //create a slot to assign an empty game object as the point to spawn the cannon
     var shooting : boolean = false;            //a boolean we can use to stop the player from shooting during the actual shot
 }

 var cannon : cannonBlast;                    //a varible used to access all other variables inside of the connected class (essentially a group)

 //class that defines the mechanics of the cannonball
 class cannonballMechanics {
     var fireRate : float = 0.5;                //a variable setting the rate of fire
     var reloadRate : float = 1.5;            //a variable setting the time for reload
     var force : int = 1000;                    //the cannons maximum power
 
     @System.NonSerialized
     var nextFire : float = 0.0;                //a variable used to determine when to fire the next cannon
 }

 var mechanics : cannonballMechanics;        //a varible used to access all other variables inside of the connected class (essentially a group)
 
 //inspector variables
 //list of default variables that can be tweaked, selected, and changed inside the inspector
 var instanceCannonball : GameObject;        //a variable holding an instance of the cannonball (which is duplicated upon firing)

 function Start () {
 }

 function FixedUpdate () {
     Shoot();                                //function put inside FixedUpdate because it handles movement over time
 }

 //function to create and shoot the cannonball
 function Shoot () {
     if (Input.GetMouseButton(0) && Time.time > mechanics.nextFire) {                                                            //checks if the user clicks the left mouse button
         instanceCannonball = GameObject.Instantiate (cannon.cannonball, cannon.spawnPos.position, cannon.spawnPos.rotation);    //creates a duplicate of the cannonball
                                                                                                                                 //at the applied position and rotation
         mechanics.nextFire = Time.time + mechanics.fireRate;
         instanceCannonball.rigidbody.AddForce (transform.forward * mechanics.force);                                            //add - or + force to the duplicated cannonball
         Debug.Log ("Fire on Target!");
         cannon.shooting = true;                                                                                                    //shows if the user is currently shooting
     } else {
         cannon.shooting = false;                                                                                                //shows if the user is not shooting
     }
 }

The error is BCE0005: Unknown identifier: 'transform'. Located inside the shoot function, it's the line: **instanceCannonball.rigidbody.AddForce (transform.forward mechanics.force);* I just don't see what's wrong with it. instanceCannonball was already declared and the variable used for adding force is declared in the class cannonballMechanics, referenced by mechanics...

Anyway, I had the same problem earlier with the error, BCE0005: Unknown identifier: 'Instantiate', located inside the shoot function, the line: instanceCannonball = GameObject.Instantiate (cannon.cannonball, cannon.spawnPos.position, cannon.spawnPos.rotation); Prior to the update I did not have to put (GameObject.) in front of Instantiate, but I checked a recent post stating the devs changed the coding. Java is more strict on defining variables. Problem is. I dont know how to edit the (transform. forward) to fix the error.

Any help or suggestions would greatly be appreciated. I'll still be attempting...