# Error while using ModelingToolkit

**URL:** <https://discourse.julialang.org/t/error-while-using-modelingtoolkit/50881>\
**Category:** Modelling & Simulations\
**Tags:** question\
**Created:** [November 27, 2020, 11:39pm UTC](https://discourse.julialang.org/t/error-while-using-modelingtoolkit/50881 "2020-11-27T23:39:49Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![contradict](https://avatars.discourse-cdn.com/v4/letter/c/ac91a4/32.png) [@contradict](https://discourse.julialang.org/u/contradict)\
**Post date:** [November 27, 2020, 11:39pm UTC](https://discourse.julialang.org/t/error-while-using-modelingtoolkit/50881/1 "2020-11-27T23:39:49Z")

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I am building a model of a pneumatic system with ModelingToolkit and have gotten stuck. I have a not-very-minimal example of the error in this [gist](https://gist.github.com/contradict/948cf099fa7e191de9a6ffff06f97f15). I haven’t been able to trim it down any more and preserve the error.

How can I debug this further?

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**Author:** ![ChrisRackauckas](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/chrisrackauckas/32/77_2.png) [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)\
**Post date:** [November 28, 2020, 3:55am UTC](https://discourse.julialang.org/t/error-while-using-modelingtoolkit/50881/2 "2020-11-28T03:55:46Z")

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Can you open an issue with this?

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**Author:** ![contradict](https://avatars.discourse-cdn.com/v4/letter/c/ac91a4/32.png) [@contradict](https://discourse.julialang.org/u/contradict)\
**Post date:** [November 28, 2020, 4:11am UTC](https://discourse.julialang.org/t/error-while-using-modelingtoolkit/50881/3 "2020-11-28T04:11:58Z")

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Issue [670](https://github.com/SciML/ModelingToolkit.jl/issues/670) opened.