Comparing 2 positions need help

here is the code from update function:

 if(canMoveUp == true)
      transform.Translate(Vector3.up * (verticalSpeed * Time.deltaTime));
      //UpButton
      if(upButtonClicked == true)
      {
          if(this.transform.position.y > playerPosition.transform.position.y+4.0f)
          {
           canMove = true;
           verticalSpeed /=3;
           upButtonClicked = false;
          }
      }

and other function:

  function GoForward()
  {
  //    if(canMove == true)
  //    this.gameObject.transform.position = new Vector3(this.gameObject.transform.position.x, this.gameObject.transform.position.y +4, this.gameObject.transform.position.z);
      playerPosition.transform.position = this.transform.position;
      upButtonClicked = true;
      canMove = false;
      verticalSpeed *=3;
  }

Im trying to make my player to go forward with fasten speed until it reaches the position i want ( +4 on y) why isnt the if statement not working in update function?