Render window output is black when I use vtkGPUVolumeRayCastMapper python

[kimia.af1998]

I can display the volume with “vtkGPUVolumeRayCastMapper” in vtk’s own vtkRenderWindow and vtkRenderWindowInteractor .it means my hardware support it but I cannot display it in “QVTKRenderWindowInteractor” of qt widget.