Trouble Adjusting Stats (MP After Casting A Spell)

I have my initial stats for MP as follows, originating from the Screen Stats Canvas:

public int playermpactual;
public int playermptotal;

void SetInitial()
{
playerhp.text = playerhpactual + “/” + playerhptotal.ToString ();
playermp.text = playermpactual + “/” + playermptotal.ToString ();
}

void Update () {
UpdateStats ();
}

public void UpdateStats()
	{
		playerhp.text = playerhpactual + "/" + playerhptotal.ToString ();
	playermp.text = playermpactual + "/" + playermptotal.ToString ();

}

When I cast a Spell, in script SpellCast attached to the player, I have the following:

private ScreenStats screenStats;
private UpdateStats updateStats;
public int MPactual;
public int MPtotal;

private Text MPText;

// Use this for initialization
void Start () {
	SetInitial ();
}

void SetInitial()
	{
		updateStats = GetComponent<UpdateStats> ();
		screenStats = GetComponent<ScreenStats> ();
		projectileplace = transform;
		MPactual = screenStats.playermpactual;
		MPtotal = screenStats.playermptotal;
		MPText = screenStats.playermp;
	}

MPactual = screenStats.playermpactual;
MPtotal = screenStats.playermptotal;

void Update () {
if (Input.GetKey(KeyCode.J))
{
throwprojectile ();
MPCost();
}
}

public void throwprojectile()
{
	GameObject projectile = (GameObject) Instantiate(projectileobject, projectileplace.TransformPoint (0, 20, 10), projectileplace.rotation * Quaternion.Euler (-90f, 0f, 0f));
		projectile.GetComponent<Rigidbody> ().AddForce (projectileplace.forward * force, ForceMode.Impulse);
		Destroy (projectile, 3);
		MPCost ();
}

	public void MPCost()
	{
		MPactual = MPactual - 8;
		Debug.Log ("MP Cost");

	}

The debug shows up but no stats change in my text.

You’re updating the value of MPActual only in your second script, not in the screenStats script. You’ll need to change

 public void MPCost()
 {
     MPactual = MPactual - 8;
     Debug.Log ("MP Cost");
 }

to something like

 public void MPCost()
 {
     MPactual = MPactual - 8;
     screenStats.playermpactual = MPactual;
     Debug.Log ("MP Cost");
 }

I still have no change. I’m going to keep working with this. Thank you for responding.