Physics2D.OverlapCircle doesnt work

Hello guys!

I have a problem with Physcis2D.OverlapCircle. In one tutorial i saw somebody use it as ground detector.

     public bool grounded;
     public float groundCheckRadius;
     public LayerMask WhatIsGround;
     public Transform groundCheck;

  void FixedUpdate()
     {
     grounded = Physics2D.OverlapCircle(groundCheck.position, groundCheckRadius, WhatIsGround);
     }

And it works nicely, so i thought i would use it to detect if player is standing on top of a platform. I tried to do it the same way but i cant get it to work properly. What i did is a created empty gameObject on each platform. Then i put a script on it where i wrote:

 public bool onTop;
 public LayerMask whatIsTop;
 public float topCheckRadius;
 public Transform topCheck;
 void FixeUpdate()
 {
     onTop = Physics2D.OverlapCircle(topCheck.position, topCheckRadius, whatIsTop);

     if (onTop)
     {
         Debug.Log("Works!");
     }
 }

Then in inspector i put the empty gameobject as the topCheck.position, i put some value for the topCheckRadius and lastly i create a layer called Top and then i select it in the WhatIsTop layermask.

But when i jump on the platform with player not$$anonymous$$ng happens.