# Problems following the Slicer extension tutorial

**URL:** <https://discourse.slicer.org/t/problems-following-the-slicer-extension-tutorial/35237>\
**Category:** Development\
**Tags:** python, tutorial\
**Created:** [April 2, 2024, 5:35pm UTC](https://discourse.slicer.org/t/problems-following-the-slicer-extension-tutorial/35237 "2024-04-02T17:35:03Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![BerDom.Ing](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/berdom.ing/32/69496_2.png) [@BerDom.Ing](https://discourse.slicer.org/u/BerDom.Ing)\
**Post date:** [April 2, 2024, 5:35pm UTC](https://discourse.slicer.org/t/problems-following-the-slicer-extension-tutorial/35237/1 "2024-04-02T17:35:03Z")

</div>

In the PerkLab’s Slicer bootcamp training [Scripting and module development tutorial](https://github.com/PerkLab/PerkLabBootcamp/blob/master/Doc/day3_2_SlicerProgramming.pptx?raw=true) , I encountered the following issues:

 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/0/7/070287385e1cbde5694af145ef35bcd876bb5dd5.png)

After downloading the 3D model, I couldn’t load it with “c = getNode(‘Cautery’)”; instead, I had to use “slicer.util.loadModel(filePath)”.

The following slice confused me:

 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/6/8/68e2a14411c5e3359f47c6c9a4173f6ce8183f9d.png)

I thought I needed to connect a signal to follow the tutorial, but the connection was already present in the example before starting to edit it.

In the next slide:

 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/8/f/8ff9e3c26ed63b00511a14b780a6b58a1f45369a.png)

I was confused because it says to replace the functions, but the function “updateGUIFromParameterNode” doesn’t exist in the example code. So, I had to think about where I needed to call that function in order to display the center of mass.

Regarding the next slide:

 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/f/c/fc97fef79bd274acd14c672ac5996059a4fa3e87.png)

I added the code to the example, but the auto-update doesn’t seem to work. I used Slicer 5.6.1 to follow the tutorial.