How can I set mirror in ofxni2?

hi
I want to reverse y-axis in stream(depth, color images) and coordinate.
so I set Stream,setMirror(true); and Stream.setMirror(false); again and again
but result is same.
Could someone help me?

void Stream::setMirror(bool v)
{
stream.setMirroringEnabled(v);
}

btw, ofxKinectForWindows2 has filp y-axis function?