Player stucks on ladder (with picture)

I have ladder script and it is work properly but when climbing down i have some bugs like the picture my player couldn't away from ladder i know i need add something stop the player when reach bottom to script but i dont know what it is. how can i fix this

Green is the ground and red is the player

This is the script;

 #pragma strict
 
 var ChController : Transform;
 var heightFactor : float = 3.2;
 private var inside = false;
 
 private var FPSInput : FPSWalkerEnhanced;
 
 function Start ()
 {
     FPSInput = GameObject.Find("Player").GetComponent(FPSWalkerEnhanced);
 }
 
 function OnTriggerEnter (Col : Collider)
 {
     if (Col.tag == "Player");
     {
         FPSInput.enabled = false;
         inside = true;
     }
 }
 
 function OnTriggerExit (Col : Collider)
 {
     if (Col.tag == "Player");
     {
         FPSInput.enabled = true;
         inside = false;
     }
 }
 
 function Update()
 {
     if (inside == true && Input.GetKey("w"))
     {
         ChController.transform.position += Vector3.up / heightFactor;
     }
         if (inside == true && Input.GetKey("s"))
     {
         ChController.transform.position += Vector3.down / heightFactor;
     }
 }