title: error: package com.google.android.gms.ads does not exist
body: <p>My Android app did work well (API 15) untill I wanted to include Google ads.
  Although google-play-services.jar is in my project library and it contains  com.google.android.gms.ads, the debugger comes up with an error: package com.google.android.gms.ads does not exist when using: </p>
  
  <pre><code>import com.google.android.gms.ads.*;
  </code></pre>
  
  <p>I tried several solutions,  but none of them worked.
  I changed from Android 4.03 API15 to Google API15 but nothing changed.
  What am I doing wrong?</p>