# Error: 0 connections

**URL:** <https://discourse.vtk.org/t/error-0-connections/1435>\
**Category:** Development\
**Created:** [July 29, 2019, 12:20pm UTC](https://discourse.vtk.org/t/error-0-connections/1435 "2019-07-29T12:20:28Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![at123](https://discourse.vtk.org/user_avatar/discourse.vtk.org/at123/32/748_2.png) [@at123](https://discourse.vtk.org/u/at123)\
**Post date:** [July 29, 2019, 12:20pm UTC](https://discourse.vtk.org/t/error-0-connections/1435/1 "2019-07-29T12:20:28Z")

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Hello, I am trying to create a silhouette which highlights a box. I create a box with the standard lines of code, using vtkCubeSource, …, and vtkActor.

664 silhouette = vtk.vtkPolyDataSilhouette()  
665 silhouette.SetCamera(self.renderer.GetActiveCamera())  
666 silhouetteMapper = vtk.vtkPolyDataMapper()  
667 silhouetteMapper.SetInputConnection(silhouette.GetOutputPort())  
668 silhouetteActor = vtk.vtkActor()  
669 silhouetteActor.SetMapper(silhouetteMapper)  
670 silhouetteActor.GetProperty().SetColor(1, 1, 0)  
671 silhouetteActor.GetProperty().SetLineWidth(5)  
672 silhouetteActor.VisibilityOff()

I also create a silhouette using:

vtkPolyDataSilhouette.SetInput(boxActor.GetMapper().GetInput()

This will update the silhouette actor so that the silhouette will be in the same position and orientation as the boxActor in 3d space and highlight its edges.

When I run the code, the silhouette appears but it is not been moved to the box’s position and orientation. Also, I get this error:

ERROR: In /work/standalone-x64-build/VTK-source/Common/ExecutionModel/vtkDemandDrivenPipeline.cxx, line 709  
vtkCompositeDataPipeline (0x4cc41d0): Input port 0 of algorithm vtkPolyDataSilhouette(0x4cefcd0) has 0 connections but is not optional.

What does this error mean and how do I fix it? By the way, I create mutliple boxActors and a silhouette for each.

Thank you. Any help would be much appreciated.

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<div class="post-metadata">

**Author:** ![lassoan](https://discourse.vtk.org/user_avatar/discourse.vtk.org/lassoan/32/50_2.png) [@lassoan](https://discourse.vtk.org/u/lassoan)\
**Post date:** [July 30, 2019, 12:56pm UTC](https://discourse.vtk.org/t/error-0-connections/1435/2 "2019-07-30T12:56:05Z")

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The error means that you did not set input for vtkPolyDataSilhouette filter. You need to call something like `silhouette.SetInputConnection(somePolyDataSource.GetOutputPort())`.