Default Need Help with Adsense

Starting to do development with android and have follow tutorial on official sites and some off site. I've having a problem with admod not displaying any ads what so ever. Tried using the app on 2 phones as well as a tablet. Still nothing!

I mainly followed:

Added the SDK JAR to your Eclipse project.
Declared in AndroidManifest.xml.
Set up network permissions in the manifest.
import the jar
did the build path
Have the admob sdk: GoogleAdMobAdsSdk-6.4.1.jar
Defining a in XML
added my ad unit : ca-app-pub-XXXXXXXXXXXXXXXX/NNNNNNNNNN

I'm really lost
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