很多種原因，這裡列舉2種如下：

1. Check for your device's ad space available(also check for padding and margin) then compare the ad size table above and choose the right value that suites. ex., if your device has 300dp width then change adSize value as 300x150 to get ads and also adjust these values for better ad presentation.
   檢查您的裝置的可用廣告空間，然後比較廣告大小表以上，例如，如果你的裝置已經300dp寬度改變adsize價值300x150得到廣告並調整這些值更好的廣告表現。
2. If you created the AdUnit id newly in Admob, the admob server is taking bit time to review & approve your native ads template. So wait for some time and try again (approx 1-2 hrs). Meanwhile make sure that your code complies with all the above 4 point
   如果你剛剛在AdMob新建了廣告 ID，AdMob的伺服器是以點時間來審查和批准你的原生廣告模板。所以，等待一段時間再試一次（約1-2小時）。