Admob not Show Ads for 1 Apps Only

[Do As Infinity Fans]

Admob accounts are in normal circumstances with no restrictions, but ads do not air on any of my  1 apps today, no violations occurred or violations on the admob dashboard.

Error in Logcat :  I/Ads: Ad failed to load : 3

the problem is only in 1 application, so far it's been normal, but today the ad is showing, sometimes it doesn't show and displays an error like this.


I know the meaning of I/Ads: Ad failed to load : 3


but why ? on my other apps it's normal