OnCollisionEnter2D has problem..

my problem is OnCollisionEnter2D function are Sometimes is not work.. and object is pass through the Collider:/ OnCollisionEnter2D is mostly works in Code.. but Sometimes this function is not works and Object are Pass through..help to me please...

this is full SourceCode here.

 using UnityEngine;
 using System.Collections;
 
 public enum PlayerState
 {
     Idle,
     Run,
     Jump,
     DoubleJump,
     Death,
 }
 
 public class Teeskii_Ctrl : MonoBehaviour {
     
     public float WalkSpeed;
     public Rigidbody2D TeeskiiRB;
     public float Jump_force = 1;
     public float DoubleJump_force = 1;
     public PlayerState PS;
     public Animator ani;
     public Game_Manager GM;
     public BoxCollider2D em;
 
     // Use this for initialization
     void Start () {
         PS = PlayerState.Idle;
     }
     
     // Update is called once per frame
     void Update () {
         TeeskiiRB.WakeUp();     
     }
     void OnTriggerEnter2D(Collider2D coll)  {
         if (coll.gameObject.tag == "DeadZone") {
             Death();
         }
     }
     void OnCollisionEnter2D (Collision2D collision) {
         if(collision.gameObject.tag == "Ground") {
             Run();
         }
         if(collision.gameObject.tag == "StartPoint")
         {
             Idle();
         }
         if(collision.gameObject.tag == "Ground" && WalkSpeed == 0) {
             Idle();
         }  
         if(collision.gameObject.tag == "Trap") {
             Death();
         }
               
     }
    
    public void JumpBtn(){
         if(PS == PlayerState.Jump) {
             DoubleJump();
             Debug.Log("DoubleJump");
         }
         if(PS == PlayerState.Run || PS == PlayerState.Idle) {
             Jump();
             Debug.Log("Jump");
         }
     }
    public void Jump() {    
        TeeskiiRB.velocity = new Vector2(0, Jump_force);
        PS = PlayerState.Jump;
        ani.SetBool("Jump", true);
        ani.SetBool("Idle", false);
        ani.SetBool("Run", false);
     }
    public void Idle()
     {
         PS = PlayerState.Idle;
         ani.SetBool("Idle", true);
         ani.SetBool("Run", false);
         ani.SetBool("Jump", false);
     }
    public void Run() {
         PS = PlayerState.Run;
         ani.SetBool("Run",true);
         ani.SetBool("Idle", false);
         ani.SetBool("Jump", false);
     }
    public void DoubleJump() {
         TeeskiiRB.velocity = new Vector2(0, DoubleJump_force);
         PS = PlayerState.DoubleJump;
         ani.SetBool("Jump", true);
         ani.SetBool("Idle", false);
         ani.SetBool("Run", false);
     }
    public void Death() {
         GM.GameOver();
         PS = PlayerState.Death;
         WalkSpeed = 0;
     }
 }