Moving an object on a Grid

I am making a grid based Turn based game and i can't seem to be able to move the object anywhere, I can select the object and store it in a variable, but when i try to change it's transform.position, it doesn't work, I am a novice programmer so i haven't the slightest idea on how to make this work, My code will be shown below.

using UnityEngine; using System.Collections.Generic; using UnityEngine.UI; using System.Linq; using Random = UnityEngine.Random;

public class PlayerBehaviour : MonoBehaviour { public int ActionsPerTurn; public Boardmanager boardManager; private Vector3 SelectedPosition; private GameObject SelectedItem; private GameObject Mbutton; private GameObject Bbutton; private GameObject Abutton; //Returns the type of object at a clicked position GameObject ClickSelect() { RaycastHit2D hit = Physics2D.Raycast(Camera.main.ScreenToWorldPoint(Input.mousePosition), Vector2.zero);

     if (hit)
     {
         return hit.transform.gameObject;
     }
     else return null;
 }
 Vector3 ClickPosition()
 {
     // collects the world position of a mouse click
     Vector3 Position = new Vector3 (Camera.main.ScreenToWorldPoint(Input.mousePosition).x,Camera.main.ScreenToWorldPoint(Input.mousePosition).y, 0f);
     return Position;
 }
 void Start () {
     boardManager = GetComponent<Boardmanager> ();
     Mbutton = GameObject.FindGameObjectWithTag("SpawnMSoldier");
     Abutton = GameObject.FindGameObjectWithTag("SpawnASoldier");
     Bbutton = GameObject.FindGameObjectWithTag("SpawnBSoldier");
     Mbutton.gameObject.SetActive(false);
     Bbutton.gameObject.SetActive(false);
     Abutton.gameObject.SetActive(false);
 }
 void Update () {
     if (Input.GetMouseButtonDown(0))
     {
         SelectedItem = ClickSelect();
         Debug.Log(ClickSelect());
         if (SelectedItem == GameObject.FindGameObjectWithTag("PlayerHQ"))
         {
             Mbutton.gameObject.SetActive(true);
             Bbutton.gameObject.SetActive(true);
             Abutton.gameObject.SetActive(true);
         }
         // if the object clicked was a Marksman
         else if(SelectedItem == GameObject.FindGameObjectWithTag("PlayerSoldierMarksman"))
         {
             //if the mouse is clicked down after the object is selected
             if (Input.GetMouseButtonDown(0))
             {
                 //setting a variable to ClickPosition to prevent recalling of the method
                 SelectedPosition = ClickPosition();
                 //if the selected position is not occupied by a game object
                 if (checkposition(SelectedPosition) == false)
                 {
                     //move the object to a position passing a parameter of SelectedPosition
                     Movement(SelectedPosition);
                 }
                 //else the movement does not occur, and a debug of a block is created
                 else
                     Debug.Log("Movement Blocked");
             }
         }
     }
 }
 void Movement(Vector3 Position)
 {
     //Sets the Selected object as the GameObject clicked on
     GameObject SelectedOb = SelectedItem;
     //Sets the Selected Objects Position to the Position clicked on
     SelectedOb.transform.position = Position;

 }
 public bool checkposition(Vector3 Position)
 {
     List<List<GameObject>> allActive = new List<List<GameObject>>();
     allActive.Add(GameObject.FindGameObjectsWithTag("Blocker").ToList());
     allActive.Add(GameObject.FindGameObjectsWithTag("PlayerHQ").ToList());
     allActive.Add(GameObject.FindGameObjectsWithTag("PlayerSoldierMarksman").ToList());
     allActive.Add(GameObject.FindGameObjectsWithTag("PlayerSoldierBasic").ToList());
     allActive.Add(GameObject.FindGameObjectsWithTag("PlayerSoldierArmored").ToList());
     allActive.Add(GameObject.FindGameObjectsWithTag("PlayerUnitRailgun").ToList());
     allActive.Add(GameObject.FindGameObjectsWithTag("EnemySoldierMarksman").ToList());
     allActive.Add(GameObject.FindGameObjectsWithTag("EnemySoldierBasic").ToList());
     allActive.Add(GameObject.FindGameObjectsWithTag("EnemySoldierArmored").ToList());
     allActive.Add(GameObject.FindGameObjectsWithTag("EnemyUnitRailgun").ToList());
     allActive.Add(GameObject.FindGameObjectsWithTag("EnemyHQ").ToList());
     
     if (allActive.Any(activeItem => activeItem.Any(activeGameObject => activeGameObject.transform.position == Position)))
     {
         return true;
     }
     return false;
 }

}