Problem with Falling Platform Script

So I basically watched GucioDev's video for the tutorial about falling platform. Here is the video

but however, for some reason I'm not able to get it working. Here is the script that I used to test it out (same script just like in the video but without "GetComponent().isTrigger = True;" part)

The Script:

using UnityEngine; using System.Collections;

public class FallingPlatform: MonoBehaviour {

 private Rigidbody2D rb2d;

 public float FallDelay;

 void Start ()
 {

     rb2d = GetComponent<Rigidbody2D>();

 }

 void OnCollisonEnter2D (Collision2D col)
 {

     if (col.collider.CompareTag("Player"))
     {

         StartCoroutine(Fall());

     }

 }

 IEnumerator Fall()
 {

     yield return new WaitForSeconds(FallDelay);
     rb2d.isKinematic = false;

     yield return 0;

 }

}