Problem with adding a obstacle to "Roll a Ball" tutorial

Hi, I recently finished the "Roll a Ball" tutorial from unity's tutorial videos and so thought, maybe I could develop the game some more by adding a spinning wall (to jump over) that kills you when you get in contact whith it. When writing the code for picking up the objects I made a mistake which made the character disappear instead of the objects:

     void OnCollisionEnter (Collider other)
     {
        if (other.gameObject.CompareTag("Pick Up"))
         {
             gameObject.SetActive(false);
         }
     }
 }

so i figured maybe I can use this failure for creating my obstacle. I added the code to the playerScript and added the necessary tags to the objects in the scene. But for some reason it is not working the way I want it to:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine.UI;
 using UnityEngine;
 
 public class PlayerController : MonoBehaviour
 {
     public float speed;
     public float jumpPower;
     private Rigidbody rb;
     private int count;
     public Text countText;
     public Text winText;
 
     // Use this for initialization
     void Start()
     {
         rb = GetComponent<Rigidbody>();
         count = 0;
         SetCountText();
         winText.text = "";
     }
 
     // Update is called once per frame
     void FixedUpdate()
     {
         float moveHorizontal = Input.GetAxis("Horizontal");
         float moveVertical = Input.GetAxis("Vertical");
 
         Vector3 movement = new Vector3(moveHorizontal, 0.0f, moveVertical);
 
         if (Input.GetKey(KeyCode.Space) && rb.transform.position.y <= 0.6250001f)
         {
             Vector3 jumping = new Vector3(0, 10, 0);
             rb.AddForce(jumping * jumpPower * Time.deltaTime);
         }
 
         rb.AddForce(movement * speed * Time.deltaTime);
     }
 
     void OnTriggerEnter(Collider other)
     {
         if (other.gameObject.CompareTag("Pick Up"))
         {
             other.gameObject.SetActive(false);
             count = count +100;
             SetCountText();
         }         
     }
 
     void SetCountText()
     {
         countText.text = "Count: " + count.ToString() + "p";
         if (count >=1100)
         {
             winText.text = "Winner!";
         }
     }
 
     void OnCollisionDie(Collider other)
     {
         if (other.gameObject.CompareTag("DeathCube"))
         {
             gameObject.SetActive(false);
         }
     }
 }

If I set the "Player" to "Is Trigger" it will fall through everything, but if I in the other hand set my object named "DeathCube to "IsTriggered the player just falls through the it and nothing more happens, no disapearing.

I should probably mention that i made a working project where the player rolls in to a wall and disappeares.

How do you fix this problem or add this kind of death-obstacle to the game?

Thanks in advance.