# Nested UDT parameters not triggering/updating

**URL:** <https://forum.inductiveautomation.com/t/nested-udt-parameters-not-triggering-updating/104713>\
**Category:** Ignition\
**Tags:** ignition81\
**Created:** [April 4, 2025, 2:04pm UTC](https://forum.inductiveautomation.com/t/nested-udt-parameters-not-triggering-updating/104713 "2025-04-04T14:04:50Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Herman\_Lundberg](https://avatars.discourse-cdn.com/v4/letter/h/df705f/32.png) [@Herman\_Lundberg](https://forum.inductiveautomation.com/u/Herman_Lundberg)\
**Post date:** [April 4, 2025, 2:04pm UTC](https://forum.inductiveautomation.com/t/nested-udt-parameters-not-triggering-updating/104713/1 "2025-04-04T14:04:50Z")

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Hi!  
I have a nested UDT: MES\_msg. It's part of a larger UDT: Engine. In Engine I have the parameters letter and number. So in the nested UDT: MES\_msg I want a parameter called name be a combination of letter and number. This works for some of my instance, but not for all and I can't see that I have made any errors on the instances where it does not work. I looks like in the image, where it looks like it's stating what the provider should do, but it's not performing the "command".

So, does anyone know what has happend when the tag provider does not resolve the parameter command/lookup/expression?

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/2/9/29d80f29bf90a93c5b4c4226a6e0e12aadc10dbc.png)

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**Author:** ![nminchin](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/nminchin/32/6911_2.png) [@nminchin](https://forum.inductiveautomation.com/u/nminchin)\
**Post date:** [April 6, 2025, 1:29pm UTC](https://forum.inductiveautomation.com/t/nested-udt-parameters-not-triggering-updating/104713/2 "2025-04-06T13:29:32Z")

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Can you paste in the json of that instance that isn't working? Really just the parameters of it