Admob is not displaying testAds

I have encountered sample problem , test ad is not displaying it 

There was a problem getting an ad response. ErrorCode: 1

If you look at the logcat logs, it will be very clear that, there is an issue with unit_id

in my case , i got the unit id like below

ca-app-pub-***74739*******~334934****

the issue here is, ca-app-pub-***74739*******~334934****

it should be  ca-app-pub-***74739*******/334934****

and ofcourse , need to provide the sufficient space for the add in the layout.

try removing layout_margin and padding which is applied in root element in the layout.