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;
         }
             

     }
 }

}