2 Image views in Android?

I have a relative layout with 2 image views in them, I try and set the xpos of image view 2 and it seems to appear inside image view 1, as if image view 1 is masking it, whats happening?

xylophoneHolder = new HorizontalScrollView(context);
    xylophoneLayout = new RelativeLayout(context);

    xylophoneHolder.addView(xylophoneLayout);

    ImageView xylophoneA = new ImageView(context);
    Bitmap bMap = BitmapFactory.decodeResource(context.getResources(),R.drawable.xylophone_a);
    xylophoneA.setImageBitmap(bMap);
    xylophoneL开发者_Go百科ayout.addView(xylophoneA);

    ImageView xylophoneAPressed = new ImageView(context);
    Bitmap bMap2 = BitmapFactory.decodeResource(context.getResources(),R.drawable.xylophone_a_pressed);
    xylophoneAPressed.setImageBitmap(bMap2);
    xylophoneAPressed.setX(100);
    xylophoneLayout.addView(xylophoneAPressed);

I think it is better to use LinearLayout with orientation instead of RelativeLayout, with LinearLayout it is worked for me