# Composes error

**URL:** https://discourse.vtk.org/t/composes-error/5780
**Category:** Web
**Created:** [May 14, 2021, 12:21pm UTC](https://discourse.vtk.org/t/composes-error/5780 "2021-05-14T12:21:58Z")
**Posts on this page:** 5
**Page:** 1

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### Author: ![Julia](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/j/2bfe46/32.png) [@Julia](https://discourse.vtk.org/u/Julia)
#### Post date: [May 14, 2021, 12:21pm UTC](https://discourse.vtk.org/t/composes-error/5780/1 "2021-05-14T12:21:58Z")

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Hi,

When importing vtkVolumeController I get the error: 'composition is only allowed when selector is single: local class name not in “.sliderIcon, “sliderIcon” is weird” ’ from the VolumeController.module.css file. How do fix this?

Thanks in advance!

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### Author: ![Sebastien\_Jourdain](https://discourse.vtk.org/user_avatar/discourse.vtk.org/sebastien_jourdain/32/100_2.png) [@Sebastien\_Jourdain](https://discourse.vtk.org/u/Sebastien_Jourdain)
#### Post date: [May 14, 2021, 2:15pm UTC](https://discourse.vtk.org/t/composes-error/5780/2 "2021-05-14T14:15:27Z")

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How do you consume vtk.js? Do you import it from source and use your build environment to bundle it inside your application?

If so, this issue is related to a missing/corrupted loader rule defined [here](https://github.com/Kitware/vtk-js/blob/master/Utilities/config/rules-vtk.js#L34-L48).

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### Author: ![Julia](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/j/2bfe46/32.png) [@Julia](https://discourse.vtk.org/u/Julia)
#### Post date: [May 14, 2021, 2:23pm UTC](https://discourse.vtk.org/t/composes-error/5780/3 "2021-05-14T14:23:00Z")

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I understand. However those lines that you have selected are already in that file… so what exactly do I need to change?

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### Author: ![Sebastien\_Jourdain](https://discourse.vtk.org/user_avatar/discourse.vtk.org/sebastien_jourdain/32/100_2.png) [@Sebastien\_Jourdain](https://discourse.vtk.org/u/Sebastien_Jourdain)
#### Post date: [May 14, 2021, 2:28pm UTC](https://discourse.vtk.org/t/composes-error/5780/4 "2021-05-14T14:28:37Z")

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I don’t know, that depends on how you’ve setup your application build system and how you use those rules. Does that mean my initial assumption was correct?

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### Author: ![Julia](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/j/2bfe46/32.png) [@Julia](https://discourse.vtk.org/u/Julia)
#### Post date: [May 14, 2021, 2:31pm UTC](https://discourse.vtk.org/t/composes-error/5780/5 "2021-05-14T14:31:37Z")

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Yes your assumption was right. I try to use the import for that, but because that does not work I retrieve it by doing: const vtkVolumeController = vtk.Interaction.UI.vtkVolumeController; and include `<script type="text/javascript" src="https://unpkg.com/vtk.js"></script> in html.` That works fine.