---
title: "Troubleshooting generating VSKs with ProCalc"
canonical: "https://help.vicon.com/space/ProCalc16/12651103/Troubleshooting%20generating%20VSKs%20with%20ProCalc"
format: markdown
---
The following tips will help you to generate and use VSKs successfully:

- On the Vicon ProCalc **Input Parameters** tab and **Variables** tab, make sure that you have selected the required option from the **Scheme** drop-down menu.
- Make sure that the static trial has been correctly labeled.
- Ensure that all the segments that you have defined in ProCalc have exactly the same names as the segments in the VST/VSK.
- After you've clicked **Update VSK**, review the log in ProCalc.   
All markers and segments that have been updated are reported.
- Check that the VST has *only 3- or 6-degree-of-freedom links* between the different segments. If the VST includes a 1- or 2-degree-of-freedom joint, replace it with a 3-degree of freedom joint.   
To do this, in Nexus, in the **Subjects Resources** tree, right-click the joint, and select **Unlink Joint**.  To re-link the two segments, use the **Labeling Template Builder** on the **Subject Preparation Tools** tab. For details, see [Updating the joints in the VST](https://vicon-help.atlassian.net/wiki/spaces/ProCalc16/pages/12649859).
- To make sure that you have updated the subject after ProCalc has run:
  - Nexus 2.9 and later: Right-click the subject and select **Refresh Subject** then **From VSK**.
  - Earlier versions of Nexus: Exit and re-enter the session (or re-start Nexus).