How can i get Camera pose at DirectX hologram

I want to get the camera pose at DirectX hologram,I follow the Doc's guid,but the return RT matrix is alway return 0,0,0 when I move the hololens. Did anybody else find sam question?

public void GetCameraLocation(HolographicFramePrediction predition)
{
SpatialLocatability locatability = m_locator.Locatability;
m_stationaryReferenceFrame = m_locator.CreateStationaryFrameOfReferenceAtCurrentLocation();
SpatialLocation location = m_locator.TryLocateAtTimestamp(predition.Timestamp, m_stationaryReferenceFrame.CoordinateSystem);
// System.Diagnostics.Debug.WriteLine("current T = " + location.Position);
System.Diagnostics.Debug.WriteLine("current R = " + location.Orientation);

}