method prints debug.log but wont update variables

ok so script is supposed to call a method from my GameManager script to increase my players health and then print the Debug.Log saying something. The Debug.Log prints but the health variable isn’t updated and I have no idea why. By the way I’m coding in C#

any help would be greatly appreciated

Heart Script:
using UnityEngine;
using System.Collections;

public class heart : MonoBehaviour {


	
	//here is a private object that we'll set as the player in start
	private GameObject target;

	public GameManager gameManager;

	void Start () {
		//once this script starts (when a heart exists) we find the player so we can have it move towards the player
		target = GameObject.Find("Player");
		//here we add a bit of force at the beginning to help give the heart a nice little animation once it is spawned
		rigidbody.AddForce(Random.Range(-600,600),0,Random.Range(-600,600));
	}
	
	void Update () {
		
		//before we do anything, we just check to see if the target is not null. this helps avoid any unwanted errors
		if(target != null){
			//here we check the square distance so we can see how close the player is to the object.
			var sqrDistance = (target.transform.position - transform.position).sqrMagnitude;
			//if the square distance is less than 16, we'll let the heart do stuff.
			if (sqrDistance <= 16){
				//before we can get the heart to move towards the player, we want to find the direction
				var dir = target.transform.position - transform.position;
				dir = dir.normalized;
				//now we apply force towards the player using the variable dir (aka direction).
				rigidbody.AddForce(dir * 1500 * Time.deltaTime);
			}
		}

	}
	
	void OnTriggerEnter (Collider other) {
		//if the tag of the trigger is in fact heart, we do stuff.


		if(other.gameObject.tag =="Player")
		{

			gameManager.IncreaseHealth();
			Debug.Log("heart collided from heart script");
			Destroy(gameObject);
		}


	}
}

GameManager script:

using UnityEngine;
using System.Collections;

public class GameManager : MonoBehaviour {



	//reference to controller2d script
	public Controller controller;

	//players life
	public Texture playersHealthTexture;


	//control screen positon
	public float screenPositionX;
	public float screenPositionY;

	//control icon size on screen
	public int iconSizeX = 25;
	public int iconSizeY = 25;

	//base lives
	 int playersHealth = 3;
	public int maxHealth = 3;

	//money
	public int gems = 0;

	//attack
	public int playerAttack = 1;

	//xp stats;
	public int curEXP = 0;
	public int maxEXP = 50;
	public int level = 1;

	bool playerStats = false;
	public GUIText statsDisplay;

	void Update ()
	{
		//level system
	if(curEXP >= maxEXP){
			levelUp();
		}
	
		if(Input.GetKeyDown(KeyCode.C)){
			playerStats = !playerStats;
		}

		if(playerStats){
			statsDisplay.text = "Level: " + level + " XP: " + curEXP + " / " + maxEXP;
		}
		else
		{
			statsDisplay.text = "";
		}
	}

	//level up system
	void levelUp(){
		Debug.Log("level up");
		curEXP = 0;
		maxEXP = maxEXP + 50;
		level++;
		
		//add stats
		maxHealth++;
		playersHealth = maxHealth;
	}


	void OnGUI()
	{
		//control players health textures
		for(int h = 0; h < playersHealth; h++)
		{
			GUI.DrawTexture(new Rect(screenPositionX + (h * iconSizeX), screenPositionY, iconSizeX,iconSizeY), playersHealthTexture, ScaleMode.ScaleToFit, true, 0);
		}

	}

	void PlayerDamaged(int damage){

		Debug.Log("PlayerDamaged");

		if(playersHealth > 0)
		{
			playersHealth -= damage;
		}

		if(playersHealth <= 0)
		{
			playersHealth = 0;
			RestartScene();
		}


	}

	public void IncreaseHealth()
	{

		playersHealth = playersHealth + 1;
		Debug.Log("increase health");
	
	}

	public void IncreaseXP()
	{
		curEXP = curEXP + 50;
		Debug.Log("increase xp");
		
	}

	public void IncreaseGems()
	{
		gems++;
		Debug.Log("increase gems");
		
	}



	void RestartScene(){
			
		Application.LoadLevel(Application.loadedLevel);
		}
	}

I tested your code and it’s working correctly, the health value is increased from 3 to 4 when an object with tag “Player” enters the “heart” object.