I've seen a lot of issues (and helped a lot of people through Team viewer with it) with the following:
The common mistake that's being made it that the SDK's for several objects are unpacked on a Windows PC, rather then on a MAC.
Once you copy over the files to the MAC, all the files are getting corrupted, and you will loose the file naming / structure.
So if you have an ZIP, RAR for the Mac, please unzip it on the MAC, and you will have zero problems with integrating it into your
Also, make sure you add the following Libraries to the project that is using Admob.
Hope this helps