Looking through your code - and please understand that my experience at this is rather limited - it looks like you might have entered an incorrect or incomplete code for your AdMob reference in the MoPub setup page (the publisher id). Your code is in a very different format to mine; it's quite possible that AdMob do this depending on your region etc, but it look suspicious to me.
To check this you need to go to MoPub Networks, click on the edit pencil next to the main AdMob link (if you click on the main link you'll then need to click on Edit Settings top right of screen). This will list your AdMob codes. The attached image shows my redacted AdMob code in Mopub - and as you can see, I have a ca-app-pub before a longer hex string than you have. Then go into AdMob and click on Monetize and then All Apps on the left side. Your AdMob Ad Unit ID will be shown here and should match what you have entered in MoPub.
If it doesn't, I think we might have found what's wrong - just copy it and paste it over what you have in MoPub/Networks/AdMob Edit/Your App ad id.
If it does match then I'm afraid I have run out of ideas. If it's any consolation, it took me a couple of goes and a second MoPub account to get my ads up and running...
Looking through this again has reminded my how appallingly unintuitive and frustrating the MoPub site is.