Admob video ad shows only once on the phone ?

i successfuly implemented admob ads , my goal is to make player able to watch a video everytime he loses the level , the video ads work just fine on the editor , but when i try it on the phone the ad play only once on the first time , when i lose the level and try to watch an ad , the ad doesnt show , so any idea ? thanks

@eni_cay There can be many reasons for that. Maybe your ad placements are new, your admob account is not verified or something else. Talking about your case this happens too often. I think it is requesting ads but it is not getting any to show. Maybe you should wait few days and it will start showing up. There are a lot of answers for questions
about advertisement. I suggest you should give it a look.