I'm trying use Unity Ads to my game, but doesn't work

I made a game and I'm using Revmob already, but I would like use Unity Ads. I already modified my AndroidManifest following the instructions of the integration guide in Unity, but it is not showing the ads.

• In AndroidManifest I modified following what Unity says;
• I added a file that came with SDK (classes.jar);
• I added the lines that came with the SDK to ProGuard.

I tried to write

<meta-data android:vale="game ID number"/>

but it doesn't work. In the integration guide of Unity they have a SDK metadata with this code:

if(UnityAds.isReady()) {
PlayerMetaData playerMetaData = new PlayerMetaData(context);
playerMetaData.setServerId("example");
playerMetaData.commit();
UnityAds.show(activity);
}

but it doesn't work either because it isn't the same language used in Eclipse, right?

I think that it isn't showing because I don't put the game ID like the others Ad Network, but how can I put the game ID?

I'm using Eclipse Luna and Java 1.7. Can someone help me?