Move the intent filter to your activity
<activity
android:name=".LockScreen"
android:clearTaskOnLaunch="true"
android:label="@string/activity_name"
android:launchMode="singleInstance"
android:theme="@android:style/Theme.NoTitleBar" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>