Need Help Finding The Problem In This Code

So I am working on a script that controls the camera. It is for a 2.5D game from the side perspective. I need the camera to remain a perspective camera so that the 3D features are still visible. The camera will move on the x/y axis so it will constantly be looking at the center of all players. It will move on the z axis to zoom in and out to make sure all players are on screen. The movement to look at the center is working, but the zoom is not. The code is done in C# and must remain so. I have taken a look at the tutorial projects, but could not find any solutions. Thank you for any help.

 using UnityEngine;
 using System.Collections;
 
 public class CameraMovement : MonoBehaviour {
 
     // Private variables
     private GameObject[] players;               // Array of players in the game
     private Camera cam;                         // The camera caponent on the main camera
     private float xpos, ypos, zpos;             // The x, y, z position the camera wants to be at
     private float minx, miny, maxx, maxy;       // The Min and Max x,y positions of players
     private bool zoomOut;                       // A Bool to track if the camera should move positivly or negativly on the z axis
 
     // Public Variables
     public float MinZoom;                       // The furthest the camera will zoom out from the players
     public float MaxZoom;                       // The closest the camera will zoom in to the players
     public float Speed = 2;                     // How fast the camera will move
 
     // Use this for initialization
     void Start ()
     {
         players = GameObject.FindGameObjectsWithTag("Player");      // Find all the players in the scene
         cam = transform.GetComponent<Camera>();                     // Store the camera caponent
     }
     
     // Update is called once per frame
     void Update ()
     {
         findCenter();       // Find center of players
         Zoom();             // Find our Min/Max positions
 
         Vector3 CamMin, CamMax;     // The Min/Max boarders of the screen
         CamMin = cam.ViewportToWorldPoint(new Vector3(0, 0, 0));        // Set the Min boarders
         CamMax = cam.ViewportToWorldPoint(new Vector3(1, 1, 1));        // Set the Max Boarders
 
         if (CamMin.x < minx - 1 || CamMin.y < miny - 1 || CamMax.x > maxx + 1 || CamMax.y > maxy + 1)   // If any player is out of the boarders
         {
             zpos = -1000;       // Set the wanted z position to zoom out direction
             zoomOut = true;     // Track that we want to zoom out
         }
 
         else    // if not then we want to zoom in
         {
             zpos = 1000;        // Set the wanted z position to zoom in direction
             zoomOut = false;    // Track that we want to zoom in
         }
 
         if (transform.position.z > MaxZoom && !zoomOut)     // If we want to zoom in but we are already max zoomed in
             zpos = MaxZoom;                    // Set the wanted z to max zoomed
 
         else if (transform.position.z < MinZoom && zoomOut)     // Else if we want to zoom out, but are already at the furthest point
             zpos = MinZoom;     // Set the wanted z to out max distance
 
         Vector3 target = new Vector3(xpos, ypos, zpos);     // Create our movement target
 
         float step = Speed * Time.deltaTime;    // Creat the step for movement
         transform.position = Vector3.MoveTowards(transform.position, target, step);     // Move the camera towards our target
 
     }
 
     void findCenter()   // A function to find our players average position
     {
         // temp cariables to store our players average x and y
         float y = 0;
         float x = 0;
 
         foreach (GameObject player in players)  // loop through all the players
         {
             // add their x and y to the temps
             y += player.transform.position.y;
             x += player.transform.position.x;
         }
 
         // find the average, and set the positions
         ypos = y / players.Length;
         xpos = x / players.Length;
     }
 
     void Zoom()     // a function to find players min/max positions
     {
         // set min/max to a value that is way out of range
         minx = 1000;
         maxx = -1000;
         miny = 1000;
         maxy = -1000;
 
         foreach (GameObject player in players)      // loop through all players
         {
             if (player.transform.position.x < minx)     // if the player's x is lower than our min
                 minx = player.transform.position.x;     // set it to the min
 
             if (player.transform.position.x > maxx)     // if the player's x is higher than our max
                 maxx = player.transform.position.x;     // set it to the max
 
             if (player.transform.position.y < miny)     // if the player's y is lower than our min
                 miny = player.transform.position.y;     // set it to the min
 
             if (player.transform.position.y > maxy)     // if the player's y is higher than our max
                 maxy = player.transform.position.y;     // set it to the max
         }
     }
 }