Audio on Collision not working C#

I've trawled Unity Answers for some examples of code playing audio on collision, and come up with some code.. but it doesn't work. I'm not sure why either.

Basically, I have a box that I want the player to be able to jump on, and I want to play a sound when they land on the box. The script is attached to the box, and this is how it looks at the moment:

 [RequireComponent(typeof(AudioClip))]
 public class landing : MonoBehaviour {
     
     public AudioClip land;
     
     void OnCollisionEnter(Collision other)
     {
         if (other.gameObject.tag == "Player")
             audio.PlayOneShot(land, 1);    
     }

I have no idea where I'm going wrong.. The audio is Ogg Vorbis, but it still refuses to play.

Any ideas?