Google Ad Manager not showing ads

Question

On integrating Google Ad Manager, it is giving me this error The Network is fine, It is loading all content.I've also switched between cellular and wifi, Still the same

{ "Code": 2, "Message": "Network error.", "Domain": "com.google.android.gms.ads", "Cause": "null", "Response Info": { "Response ID": "null", "Mediation Adapter Class Name": "", "Adapter Responses": [] } }

kotlin file like:

`adView.visibility = View.VISIBLE val adRequest: AdRequest = AdRequest.Builder().build() adView.loadAd(adRequest)

            adView.adListener = object: AdListener() {
                override fun onAdClicked() {
                    // Code to be executed when the user clicks on an ad.
                    // Toast.makeText(context, "Clicked on Ad!", Toast.LENGTH_LONG).show()
                }

                override fun onAdClosed() {
                    // Code to be executed when the user is about to return
                    // to the app after tapping on an ad.
                    // Toast.makeText(context, "Loaded Ad!", Toast.LENGTH_LONG).show()
                }

                override fun onAdFailedToLoad(adError : LoadAdError) {
                    // Code to be executed when an ad request fails.
                    // Toast.makeText(context, "ErrorV : " +adError, Toast.LENGTH_LONG).show()
                    Log.e("ASA: ", "Error: "+adError)
                }

                override fun onAdImpression() {
                    // Code to be executed when an impression is recorded
                    // for an ad.
                    // Toast.makeText(context, "Ad Impression!", Toast.LENGTH_LONG).show()
                }

                override fun onAdLoaded() {
                    // Code to be executed when an ad finishes loading.
                    // Toast.makeText(context, "Loaded Ad!", Toast.LENGTH_LONG).show()
                }


                override fun onAdOpened() {
                    // Code to be executed when an ad opens an overlay that
                    // covers the screen.
                    // Toast.makeText(context, "Open Ad!", Toast.LENGTH_LONG).show()
                }
            }`

Please Help!