Clamps not working! :(

I have 3 or 4 clamps and they dont seem to be working :(

using UnityEngine; using System.Collections;

public class CameraController : MonoBehaviour {

 public int Sensitivity;

 private float MouseY;
 private float MouseYSet;
 private float XRot;
 private float YPos;
 private float ZPos;

 public GameObject CameraTarget;

 void Start () {

 }

 void Update () {
     // Rotation controls
     MouseY += Input.GetAxisRaw ("Mouse Y");
     XRot = transform.rotation.x;
     YPos = transform.position.y;
     ZPos = transform.position.z;
     XRot = Mathf.Clamp (XRot, 90, 270);
     YPos = Mathf.Clamp (YPos, CameraTarget.transform.position.y, CameraTarget.transform.position.y + 50);
     ZPos = Mathf.Clamp (ZPos, CameraTarget.transform.position.z - 40, CameraTarget.transform.position.z);
     if (MouseYSet != MouseY)
     {
         transform.Rotate (new Vector3 (-(MouseY - MouseYSet) * Sensitivity * 10, 0, 0));
         transform.Translate (new Vector3 (0, -(MouseY - MouseYSet) * Sensitivity * 10, -(MouseY- MouseYSet) * Sensitivity * 10));
         MouseYSet = MouseY;
     }

 }

}