Unity ads: ad not showing

So I have been trying to get ads working in my game but I’ve had no luck, I’ve looked around and couldn’t find an answer.
The ad in the editor returns true but on mobile nothing happens.
This is my code:
sing UnityEngine;
using UnityEngine.Advertisements;

public class adsys : MonoBehaviour {
		public void ShowAd()
		{
		if (Advertisement.IsReady("defaultZone") && PlayerPrefs.GetInt("LS") >= 6)
			{
			Advertisement.Show("defaultZone");
			PlayerPrefs.SetInt ("LS", 0);
			}
		}

}

Every time the player loses the game the LS gets a ++:

PlayerPrefs.SetInt("LS", PlayerPrefs.GetInt ("LS")+1);

it’s probably something stupid I overlooked but I really can’t seem to fix it, thanks for the help!

I knew it was a stupid thing, I somehow thought the showad() method was the start one…

using UnityEngine;
using System.Collections;
using UnityEngine.Advertisements;

public class adsys : MonoBehaviour {

	void Start()
	{
		Debug.Log (PlayerPrefs.GetInt ("LS").ToString ());
		if(PlayerPrefs.GetInt("LS") >= 6)
		{
		StartCoroutine(ShowAd());
			PlayerPrefs.SetInt ("LS", 0);
		}
	}

	IEnumerator ShowAd() {
		while (!Advertisement.IsReady()) {
			yield return null;
		}
		Advertisement.Show();
	}

}

Here’s the fixed code for anyone as stupid as me :stuck_out_tongue: