[vtkusers] Bad homogeneous coordinates

[David Català]

hi everyone,
I have a error:
"ERROR: In D:\vtk411\Rendering\vtkPicker.cxx, line 195
vtkCellPicker (0x0CC55E58): Bad homogeneous coordinates"
This error is the output of a vtkOutputWindow.

Can anybody tell me how disable vtkOutputWindow?
and, why i produce"Bad Homogeneous coordinates", why "worldCoords[3]
== 0.0"?

The code of vtkPicker.cxx, line 195 is:
 // Convert the selection point into world coordinates.
  //
  renderer->SetDisplayPoint(selectionX, selectionY, selectionZ);
  renderer->DisplayToWorld();
  worldCoords = renderer->GetWorldPoint();
  if ( worldCoords[3] == 0.0 )
    {
    vtkErrorMacro(<<"Bad homogeneous coordinates");
    return 0;
    }

Thanks,
David