We are trying to draw something with the scene2D from libGDX. We have our main activity then use the extends Androidapplication to initialize our testgame class. Here we define our screen and then make our stage and actors in the screen class.
Problem is that we are getting the same error over and over: >
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.gamepadTest.app/com.gamepadTest.app.MainActivity}: android.content.ActivityNotFoundException: Unable to find explicit activity class {com.gamepadTest.app/com.gamepadTest.app.TestGame}; have you declared this activity in your   AndroidManifest.xml? 
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2137)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
            at android.app.ActivityThread.access$600(ActivityThread.java:141)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:5103)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:525)
            at     com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
            at dalvik.system.NativeStart.main(Native Method)
            Caused by: java.lang.ClassNotFoundException: Didn't find class     "com.gamepadTest.app.MainActivity" on path: DexPathList[[zip file     "/data/app/com.gamepadTest.app-1.apk"],nativeLibraryDirectories=[/data/app-   lib/com.gamepadTest.app-1, /system/lib]]
            at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:53)
            at java.lang.ClassLoader.loadClass(ClassLoader.java:501)
            at java.lang.ClassLoader.loadClass(ClassLoader.java:461)
            at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2128)
            
> at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
            at android.app.ActivityThread.access$600(ActivityThread.java:141)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:5103)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:525)
            at      com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
            at dalvik.system.NativeStart.main(Native Method)
Have a look:
import android.os.Bundle;
import com.badlogic.gdx.backends.android.AndroidApplication;
import com.badlogic.gdx.backends.android.AndroidApplicationConfiguration;
public class MainActivity extends AndroidApplication {
    private TestGame testGame = new TestGame();
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        AndroidApplicationConfiguration cfg = new AndroidApplicationConfiguration();
        initialize(testGame, cfg);
    }
}
import com.badlogic.gdx.Game;
public class TestGame extends Game
{
    TestScreen testScreen;
    @Override
    public void create() {
        testScreen = new TestScreen();
        setScreen(testScreen);
    }
    @Override
    public void dispose() {
        testScreen.dispose();
    }
}
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.Screen;
import com.badlogic.gdx.graphics.GL10;
import com.badlogic.gdx.scenes.scene2d.Stage;
public class TestScreen implements Screen {
    private Stage stage;
    private TestActor testActor;
    public TestScreen() {
        stage = new Stage();
        Gdx.input.setInputProcessor(stage);
        testActor = new TestActor();
        stage.addActor(testActor);
    }
    public void resize(int width, int height) {
        stage.setViewport(800, 600, false);
        stage.getCamera().translate(-stage.getGutterWidth(), -stage.getGutterHeight(), 0);
    }
    @Override
    public void render(float delta) {
        Gdx.gl.glClearColor(0, 0, 0, 1);
        Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT);
        stage.act(delta);
        stage.draw();
    }
    @Override public void dispose() {
        stage.dispose();
    }
    @Override public void show() {}
    @Override public void hide() {}
    @Override public void pause() {}
    @Override public void resume() {}
}
import com.badlogic.gdx.graphics.g2d.SpriteBatch;
import com.badlogic.gdx.graphics.glutils.ShapeRenderer;
import com.badlogic.gdx.scenes.scene2d.Actor;
public class TestActor extends Actor{
    private ShapeRenderer renderer;
    @Override
    public void act(float delta) {
        super.act(delta);
        renderer = new ShapeRenderer();
    }
    @Override
    public void draw (SpriteBatch batch, float parentAlpha) {
        batch.end();
        renderer.setProjectionMatrix(batch.getProjectionMatrix());
        renderer.setTransformMatrix(batch.getTransformMatrix());
        renderer.translate(getX(), getY(), 0);
        renderer.begin(ShapeRenderer.ShapeType.Point);
        renderer.rect(0, 0, 100, 100);
        renderer.end();
        batch.begin();
    }
}
UPDATE:
Here is my manifest:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.gamepadTest.app"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
    android:minSdkVersion="11"
    android:targetSdkVersion="19" />
<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name="com.gamepadTest.app.MainActivity"
        android:label="@string/app_name">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>
</manifest>