diff --git a/Assets/Script/SDKManager/AdsSDKManager/MaxAdsManager/MaxAdsManager.cs b/Assets/Script/SDKManager/AdsSDKManager/MaxAdsManager/MaxAdsManager.cs
index f34f90e..39a623c 100644
--- a/Assets/Script/SDKManager/AdsSDKManager/MaxAdsManager/MaxAdsManager.cs
+++ b/Assets/Script/SDKManager/AdsSDKManager/MaxAdsManager/MaxAdsManager.cs
@@ -180,6 +180,7 @@ namespace WZ
 
         private bool IsAdsAvailable(string adUnit, AdsType adsType)
         {
+            if (string.IsNullOrEmpty(adUnit)) return false;
             if (adsType == AdsType.Rewarded)
             {
                 if (!_maxRewardedUnits.Contains(adUnit)) return false;