camera falling down when following player!!

I tried many scripts but nothing works. I will go crazy. what can i do for this?? when my player holding to rope main camera slips down.

Please take a look: https://sendvid.com/mziuem3u

Follow Script:

 #pragma strict
   
 var cameraTarget : GameObject; // Inspector> Assign the Camera Target NON è il target della camera ma la posizione che vuole raggiungere la camera
  
 var smoothTime : float = 0.1;              // Delay in seconds to follow Player
 var cameraFollowX : boolean = true;        // Inspector> if is checked -> The Camera will follow X position of cameraTarget
 var cameraFollowY : boolean = true;        // Inspector> if is checked -> The Camera will follow Y position of cameraTarget
 var cameraFollowHeight : boolean = false;  // if true the Camera Y Position = cameraHeight
 var cameraHeight : float = 2.5;            // cameraHeight
 var velocity : Vector2;
 var offset : float;
 private var thisTransform : Transform;    
  
 function Start ()
 {
   thisTransform = transform;
 }
  
 function Update () 
 {
  
 if (cameraFollowX) // if cameraFollowX = true = Inspector is checked
 {
   thisTransform.position.x = Mathf.SmoothDamp (thisTransform.position.x, cameraTarget.transform.position.x + offset, velocity.x, smoothTime);
 }
  
 if (cameraFollowY) // if cameraFollowY = true = Inspector is checked
 {
   thisTransform.position.y = Mathf.SmoothDamp (thisTransform.position.y, cameraTarget.transform.position.y, velocity.y, smoothTime);
 }
  
 if (!cameraFollowY && cameraFollowHeight)     // if cameraFollowY = false = Inspector is unchecked AND cameraFollowHeight = true = Inspector is checked
 {
   GetComponent.<Camera>().transform.position.y = cameraHeight; // The Camera Y position = cameraHeight
 }
  
 }