Missing 'name' key attribute on element activity as AndroidManifest.xml in android ?

Specificy a name attribute on the Application tag of your Android manifest file:

<application
     // Declare a name tag here:
         android:name=""
         android:icon="@drawable/ic_launcher"
         android:label="@string/app_name"
         android:theme="@style/AppTheme" >

         <activity
              android:name=".MainActivity"
              android:label="@string/title_activity_main" >
         </activity>
</application>