Mouse click not working

Hi I am making a game where I need to click on a column and it will pause for a second. This is the code I am using however it does not seem to work. I am not getting any errors, it just isnt working and it is not printing anything in the console. thanks!
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class SquareScript : MonoBehaviour {

public float moveSpeed;
private float moveTimeCounter;
public float moveDistance;
private Vector3 endPos;

private float averageDTime;
private int averageDTCounter;
private bool moving;
public Main refToMain;

// Use this for initialization
void Start () {
	refToMain = GameObject.FindGameObjectWithTag ("GameController").GetComponent<Main> ();

}

// Update is called once per frame
void Update () {
	if (transform.position.y > 8 || transform.position.y < -8) {
		Destroy (gameObject);
	}
		
		

	if (moving) {
		
		if (moveTimeCounter <= 1) {
			moveTimeCounter += Time.deltaTime * moveSpeed;
			averageDTime += Time.deltaTime;
			averageDTCounter++;
		} else {
			moveTimeCounter = 0;
			moving = false;
			//print (averageDTime / averageDTCounter);
			averageDTCounter = 0;
			averageDTime = 0;

		}
		transform.position = Vector3.Lerp (transform.position, endPos, moveTimeCounter);

	}
}

public void Move(string moveDirection){
	moving = true;
	if (moveDirection == "up") {
		 endPos = new Vector3 (transform.position.x, transform.position.y + moveDistance, 0);
	}
	if (moveDirection == "down") {
		endPos = new Vector3 (transform.position.x, transform.position.y - moveDistance, 0);
	}

}
public void OnMouseStay(){
	if (Input.GetMouseButton (0)) {
		print ("clicked");

		if (tag == "SquareLeft") { 
			refToMain.leftColumnOn = false;
			print ("left");
		}

		if (tag == "SquareMid") { refToMain.midColumnOn = false;
		}

		if (tag == "SquareRight") { refToMain.rightColumnOn = false;
		}
			

	}
}

}

There’s no such thing called OnMouseStay().

Do you mean OnMouseOver()?