error

12-07 12:06:48.310: E/AndroidRuntime(8144): FATAL EXCEPTION: main
12-07 12:06:48.310: E/AndroidRuntime(8144): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.ses/com.example.ses.MainActivity}: java.lang.ClassNotFoundException: Didn't find class "com.example.ses.MainActivity" on path: /data/app/com.example.ses-1.apk
12-07 12:06:48.310: E/AndroidRuntime(8144):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2106)

class Face_Detection_View extends View {
    private static final int MAX_FACES = 10;
    private static final String IMAGE_FN = "face.jpg";
    private Bitmap background_image;
    private FaceDetector.Face[] faces;
    private int face_count;
    
    private PointF tmp_point = new PointF();
    private Paint tmp_paint = new Paint();

    public Face_Detection_View(Context context) {
        super(context);

android versiyonum bu

 <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="18" />