Issue with a for loop.

Hello, I have been experimenting with Dijkstra's path finding. I have one for loop that goes through each node and checks its y+1 position to the position of the next node in the list to see if it is above it, if it is, it creates a connection by storing the the second node in a list of connections in the first node. This works fine. The next section of the code does the exact same thing however it looks for y-1 to see if there is a node below the current node in the list. This for loop is not working. Using the debug console I can see that the for loop is triggered, however the checkDown() method returns false 100% of the time and I am unsure why. Any help would be appreciated, code below.

using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using UnityEngine;

/// /// The Graph. /// public class Graph : MonoBehaviour {

 [SerializeField]
 public List<Node> m_Nodes = new List<Node> ();
 [SerializeField]
 public Node newNode;

 private BoardCreator board;
 private int nodeListSize;

 int nextnameNumber = 0;

 public virtual List<Node> nodes
 {
     get
     {
         return m_Nodes;
     }
 }
 void Start(){

     board = GameObject.FindObjectOfType<BoardCreator> ();

     setUpNodes ();

     setupConnections();


 }

 public void setUpNodes(){
     //the two nested for loops will loop through every tile in BoardCreator
     for (int i = 0; i < board.tiles.Length; i++) {
         for (int j = 0; j < board.tiles [i].Length; j++) {

             if (board.floorCheck (i, j) == true) {//if the position in x,y returns true in the floorCheck
                 Vector3 newNodePos = new Vector3 (i, j, 0);//set the nodes position to the true x,y coords
                 Node newNodeInstance = Instantiate (newNode, newNodePos, Quaternion.identity) as Node; //instantiate as a node
                 newNodeInstance.name = "Node" + nextnameNumber;//give the instantiated node a unique name
                 m_Nodes.Add (newNodeInstance);//add the new node to the list of nodes
                 newNodeInstance.transform.parent = this.transform;//set the node to be a child of the graph
                 nextnameNumber++;//increase the number added to the end of the node name by 1 every iteration
             }
         }
     }
 }
 public void setupConnections(){
     Debug.Log ("I made it to up connections!");
     nodeListSize = m_Nodes.Count;
     //this works to get the dynamic size of the node list when the graph is called to be created
     //this will be used in conjunction with the code below to establish connections between nodes
     //m_Nodes[0].connections.Add(m_Nodes[3]);
     //m_Nodes[0].connections.Add(m_Nodes[2]);
     //the above also works

     for (int i = 0; i < nodeListSize - 1; i++) {
         if (checkAbove (m_Nodes [i], m_Nodes [i+1]) == true) {
             m_Nodes [i].connections.Add (m_Nodes [i+1]);
             Debug.Log ("I added an up connection");
         }

     }
     for (int x = 0; x < nodeListSize - 1; x++) {
         if (checkBelow (m_Nodes [x], m_Nodes [x+1]) == true) {
             m_Nodes [x].connections.Add (m_Nodes [x+1]);
             Debug.Log ("I added a down connection");
         }

     }

 }


 public bool checkAbove(Node thisNode, Node nextNode){
     bool isAbove;
     if (Mathf.Approximately(thisNode.transform.position.y + 1, nextNode.transform.position.y)) {
         Debug.Log ("checkAbove is true");
         isAbove = true;
         return isAbove;
     } else {
         Debug.Log ("checkAbove is false");
         isAbove = false;
         return isAbove;
     }
 }
 public bool checkBelow(Node thisNode, Node nextNode){
     bool isBelow;
     if (Mathf.Approximately(thisNode.transform.position.y - 1, nextNode.transform.position.y)) {
         Debug.Log ("checkBelow is true");
         isBelow = true;
         return isBelow;
     } else {
         Debug.Log ("checkBelow is false");
         isBelow = false;
         return isBelow;
     }
 }