Android示例应用未出现

新安卓开发者来了。我在听一个关于 http://www.vogella.de/

当另一个应用程序工作时,它不会得到两行“找不到启动程序活动!”和“启动将只同步设备上的应用程序包。”

我看到的是:

------------------------------
...] Android Launch!
...] adb is running normally.
...] No Launcher activity found!
...] The launch will only sync the application package on the device!
...] Performing sync
...] Automatic Target Mode: using existing emulator 'emulator-5554' running compatible AVD 'TestDevice'
...] Uploading de.vogella.android.preferences.apk onto device 'emulator-5554'
...] Installing de.vogella.android.preferences.apk...
...] Success!
...] \de.vogella.android.preferences\bin\de.vogella.android.preferences.apk installed on device
...] Done!

这是我的Android清单文件中的文本

<manifest 
    xmlns:android="schemas.android.com/apk/res/android";
    package="de.vogella.android.preferences" 
    android:versionCode="1" 
    android:versionName="1.0"> 
    <application android:icon="@drawable/icon" android:label="@string/app_name"> 
        <activity android:name=".HelloPreferences" android:label="@string/app_name">
        </activity> 
        <activity android:label="Preferences" android:name="Preferences">
        </activity>
    </application>
    <uses-sdk android:minSdkVersion="8" />
</manifest>