# Tag Value Changed Script : only works with override

**URL:** <https://forum.inductiveautomation.com/t/tag-value-changed-script-only-works-with-override/110410>\
**Category:** Ignition\
**Tags:** ignition81\
**Created:** [September 5, 2025, 1:20pm UTC](https://forum.inductiveautomation.com/t/tag-value-changed-script-only-works-with-override/110410 "2025-09-05T13:20:03Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Stef\_Van\_Poucke](https://avatars.discourse-cdn.com/v4/letter/s/dec6dc/32.png) [@Stef\_Van\_Poucke](https://forum.inductiveautomation.com/u/Stef_Van_Poucke)\
**Post date:** [September 5, 2025, 1:20pm UTC](https://forum.inductiveautomation.com/t/tag-value-changed-script-only-works-with-override/110410/1 "2025-09-05T13:20:03Z")

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Dear experts.  
I have a UDT with a tag value changed script.  
When I create an instance of this UDT the script doesn’t get executed (I start with a log.trace)

When I override the Value Changed script but don’t make any actual changes it suddenly starts to work.

Any idea what might cause this behaviour?

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<div class="post-metadata">

**Author:** ![Chris\_Bingham](https://avatars.discourse-cdn.com/v4/letter/c/e5b9ba/32.png) [@Chris\_Bingham](https://forum.inductiveautomation.com/u/Chris_Bingham)\
**Post date:** [September 5, 2025, 1:38pm UTC](https://forum.inductiveautomation.com/t/tag-value-changed-script-only-works-with-override/110410/2 "2025-09-05T13:38:14Z")

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A good starting point:

> [@Tag Change Missed Events](https://forum.inductiveautomation.com/t/tag-change-missed-events/37764):
>
> What does the missed events parameter mean in a tag change script? Does it mean that one script failed to execute because it changed so fast? I have several tags that change at fast at most 10 per second. Does the missed event true mean it failed to a tag change script on a a change?

You might check your gateway Status / Diagnostics / Running Scripts page to quickly visualize any long running scripts.

You might also find [Tag Diagnostics](https://www.docs.inductiveautomation.com/docs/8.1/platform/tags/tag-diagnostics) useful. Right-click on a tag –\> View Diagnostics to check for anything out-of-norm.