Roll a Ball PickUp Issues

So i’m doing the first tutorial on the Unity website. Everything works fine, except when I try and pick up the little ‘gems’. My ball just passes straight through it and I get this error:

UnityException: Tag: Pick Up is not defined.
PlayerController.OnTriggerEnter (UnityEngine.Collider other) (at Assets/Scripts/PlayerController.cs:30)

Common Errors Which I’ve Checked isn’t mine:

My tag is named correctly, I copied and pasted from the script, case-sensitive and everything.

IsTrigger is on for all my objects

I can enter playmode so it’s most likely not a scripting error.

All pickups and my player sphere both have colliders.

I have had similar problem. For me, problem was about giving two distinct names for my tag and the “Gems” in my script.
That means, in my script I wrote “(other.gameObject.CompareTag. (“Pick Up”)” because that was a way it was wrote in the tutorial. But for the tag, I already used name in my homelaunguage - “Punkt”
So I had script with an object called “Pick Up” and Tag called “Punkt”

When I realised it cause an error, I simply change my script name from “Pick Up” to “Punkt”. Everything goes right.

I hope it was helpful. My english is a little bit vague, so no hesitate asking for explaining anything again.