admob Ads doesn't show when im using the real Ad Id, but if Im using test ad id it show up

hello guys, i have been developed my first game and i want to add ads in it and here is the code

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using GoogleMobileAds.Api;  


public class bannerads : MonoBehaviour {
	BannerView bannerView;
	public GameObject shopscreen;


	void Start () {
		
		// Create an empty ad request.
		AdRequest request = new AdRequest.Builder()
			.AddTestDevice(AdRequest.TestDeviceSimulator)       // Simulator
			.AddTestDevice("xxxx46bda46fa8b9xxxxxxxxxx")  // My test device.
			.Build();
		// Load the banner with the request.
		// Create a 320x50 banner at the top of the screen.
		bannerView = new BannerView("ca-app-pub-xxxxxxxxxxxxx/xxxxxxxx", AdSize.SmartBanner, AdPosition.Bottom);
		bannerView.LoadAd(request);
	}
		
	void Update()
	{
		
		if (shopscreen.activeInHierarchy == true)
		{
			bannerView.Show ();
			Debug.Log("SHOW AD banner");
		}
		else if(shopscreen.activeInHierarchy == false)
		{
			bannerView.Hide();
		
	}

	}

}

when I testing it with test Ad id, the ads show up in my game when I build and run it in android.
but when I using my Admob real Ad Id, nothing show up

when I looking in the internet for the solution, many said I must wait some hour before the ads sho up
but its already 1 day and my live ads still doesn’t show up

help me guys

note: im already change my testdevice id code with my android device id too

sry for bad english

Sorry Guys, My bad
I just found the solution, and its becaus the TestDevice ID, its case sensitive and all of my device id use uppercase
im very newbie in this, forgive my dumb question

How do I get my TestDevice ID?