Can't draw a rectangle into camera frame with opencv android

Hi guys!
I’m trying doing something like this OpenCV (Java) : Draw a rectangle region on Camera View is the same work but for me it does not work. I’m using opencv for android version 3.4.10 I also tested it using opencv 3.4.7 but does not work. Here is my code:

    public Mat onCameraFrame(CameraBridgeViewBase.CvCameraViewFrame inputFrame) {
        mRgba = inputFrame.rgba();
        int w = mRgba.width();
        int h = mRgba.height();

        Imgproc.rectangle(mRgba, new Point(w * 1 / 3, h * 1 / 3), new Point(
                w * 2 / 3, h * 2 /  3 ), new Scalar( 255, 0, 0 ), 5);
        return mRgba;

The application only is showing the normal image without any rectangle.
However I can see the letters of the fps in blue color.


I don’t know really why it does not work, please guys if you have any idea about how fix it I will appreciate it. Thanks in advance.

PD: I’m using CameraBridgeViewBase… this is an small code from my onCreate() method in my

 cameraBridgeViewBase =(JavaCameraView)findViewById(;

I fixed it in the OnCreate I had this:
cameraBridgeViewBase = (JavaCameraView) findViewById (;

I changed it to cameraBridgeViewBase = (CameraBridgeViewBase) findViewById (;

This made me try on three versions of opencv …