[vtkusers] vtkImageMedian3D with Custom Source

[Georg Ziegler]

Hello!

I am not very experienced with the workings of the new pipeline but I 
have managed to write a custom source similar to the one in this example:
http://www.vtk.org/Wiki/VTK_Examples_vtkImageAlgorithm_Source

Then I have built a pipeline like so:

vtkImageMedian3D->SetInputConnection(vtkMyCustomSource->GetOutputPort());
vtkVolumeRayCastMapper->SetInputConnection(vtkImageMedian3D->GetOutputPort());

Unfortunately, this setup does not produce a volume as expected.
If I connect my custom source directly to the mapper I do get a result.
vtkVolumeRayCastMapper->SetInputConnection(vtkMyCustomSource->GetOutputPort());

Can you point me to where the problem might be?
Do I have to implement another method in my custom source besides 
RequestData()?

Regards,
Georg