title: Why i am not able to load Advertisement sometimes?
body: <p>I have implemented AdMob to My Application from this Docunemtation: <a href="http://code.google.com/mobile/ads/docs/android/fundamentals.html" rel="nofollow">Here</a></p>
  
  <p>I can see the ad perfectly as I want. But some times I cant able to see the advertisements. If i refresh the activity, it will show me the Advertisement again. and ita work perfectly.</p>
  
  <p>But when i am not able to see the advertisement at that time i got the message at catlog like:</p>
  
  <pre><code>09-27 12:58:54.451: INFO/Ads(940): onFailedToReceiveAd(Ad request successful, but no ad returned due to lack of ad inventory.)
  </code></pre>
  
  <p>I dont know where is the Problem ?
  Why I am not able to see the Add sometimes ??
  Please give the way if I am wrong regarding it.
  Thanks.</p>