Android Cast v3: cannot find any device

Question

I am trying to integrate android cast v3 in my application and cannot make it work.

I did exactly what is written in this google document: https://developers.google.com/cast/docs/android_sender_integrate (up to the heading: "Configure device discovery")

And the dialog that opened when I click on MediaRouteButton cannot find any device until the success of the youtube application detects my Android device.

what did I miss?

// the code of the CastOptionsProvider: class CastOptionsProvider implements OptionsProvider { @Override public CastOptions getCastOptions(Context appContext) { return new CastOptions.Builder().setReceiverApplicationId( CastMediaControlIntent.DEFAULT_MEDIA_RECEIVER_APPLICATION_ID).build(); } @Override public List<SessionProvider> getAdditionalSessionProviders(Context context) { return null; } } // the code in the custom view: mMediaRouteButton = (MediaRouteButton)findViewById(R.id.media_route_button); CastButtonFactory.setUpMediaRouteButton(getContext(), mMediaRouteButton); mCastContext = CastContext.getSharedInstance(getContext()); 

and in the manifest (inside the application tag):

 <meta-data android:name="com.google.android.gms.cast.framework.OPTIONS_PROVIDER_CLASS_NAME" android:value="com.bla-company-bla.core.cast.CastOptionsProvider"/>