Null Pointer Exception when adding GroundOverlay to gMap : <p>i'm working on a project for indoor navigation and need to add a groundOverlay with the floorplan of the building. I've followed the guidelines on the Documentation from Google dev site. But its giving me NullPointerException when i try to add the overlay to the map.
Heres my code:</p>

<pre><code>@Override
public void onMapReady(GoogleMap googleMap) {
    mMap = googleMap;

    mMap.setIndoorEnabled(true);
    mMap.setOnIndoorStateChangeListener(this);
    mMap.setPadding(0,0,50,0);
    mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(-28.666957, -55.994823), 19));

    //add mapOverlay
    LatLngBounds iffBounds = new LatLngBounds(
            new LatLng(-28.667177,-55.995104),
            new LatLng(-28.667061,-55.994443)
    );
    GroundOverlayOptions iffMap = new GroundOverlayOptions()
            .image(BitmapDescriptorFactory.fromResource(R.raw.piso_1))
            .positionFromBounds(iffBounds);


    mapOverlay = mMap.addGroundOverlay(iffMap);
}
</code></pre>

<p>I have tried debbuging the code and i can't see anything wrong, everything is being correctly instantiated, but when it executes the last line</p>

<pre><code>mapOverlay = mMap.addGroundOverlay(iffmap);
</code></pre>

<p>My app crashes.</p>

<p>Here's the StackTrace from logCat:</p>

<pre><code>E/AndroidRuntime: FATAL EXCEPTION: main
              Process: br.com.imerljak.vegvisir, PID: 2390
              java.lang.NullPointerException: null reference
                  at maps.w.c.a(Unknown Source)
                  at maps.ad.g$a.&lt;init&gt;(Unknown Source)
                  at maps.ad.g.a(Unknown Source)
                  at maps.ad.w.&lt;init&gt;(Unknown Source)
                  at maps.ad.u.a(Unknown Source)
                  at vo.onTransact(:com.google.android.gms.DynamiteModulesB:182)
                  at android.os.Binder.transact(Binder.java:380)
                  at com.google.android.gms.maps.internal.IGoogleMapDelegate$zza$zza.addGroundOverlay(Unknown Source)
                  at com.google.android.gms.maps.GoogleMap.addGroundOverlay(Unknown Source)
                  at br.com.imerljak.vegvisir.MapsActivity.onMapReady(MapsActivity.java:62)
                  at com.google.android.gms.maps.SupportMapFragment$zza$1.zza(Unknown Source)
                  at com.google.android.gms.maps.internal.zzt$zza.onTransact(Unknown Source)
                  at android.os.Binder.transact(Binder.java:380)
                  at xz.a(:com.google.android.gms.DynamiteModulesB:82)
                  at maps.ad.u$5.run(Unknown Source)
                  at android.os.Handler.handleCallback(Handler.java:739)
                  at android.os.Handler.dispatchMessage(Handler.java:95)
                  at android.os.Looper.loop(Looper.java:135)
                  at android.app.ActivityThread.main(ActivityThread.java:5312)
                  at java.lang.reflect.Method.invoke(Native Method)
                  at java.lang.reflect.Method.invoke(Method.java:372)
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:901)
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:696)
</code></pre>

<p>PS: if anyone has any tips that will help me developing this app (like a good API for indoor navigation) i will be grateful :)</p>
