[Paraview] Reader did not create output

[David Doria]

I created a vtk class vtkPTXReader which is working as expected when
used from c++. I am trying to make a reader plugin for Paraview, but I
am getting the following error when I try to open a PTX file in
Paraview:

ERROR: In /home/doriad/src/ParaView3/VTK/Filtering/vtkDemandDrivenPipeline.cxx,
line 690
vtkCompositeDataPipeline (0x9657d68): Algorithm
vtkPTXReader(0x964f6a0) did not create output for port 0 when asked by
REQUEST_DATA_OBJECT and does not specify any DATA_TYPE_NAME.

My class and plugin xml files can be found here:
http://www.rpi.edu/~doriad/Paraview_List/PTX/

Can anyone see what the problem may be?

Once I get this figured out, I plan to add it to:
http://www.paraview.org/Wiki/Plugin_HowTo#Adding_a_Reader
as it currently doesn't have all the necessary information (namely the
main xml file).

Thanks,

David