# DataSet Custom property on UDT has value of \[Unknown Type\] when written

**URL:** <https://forum.inductiveautomation.com/t/dataset-custom-property-on-udt-has-value-of-unknown-type-when-written/66022>\
**Category:** Ignition\
**Tags:** ignition81\
**Created:** [November 2, 2022, 6:55pm UTC](https://forum.inductiveautomation.com/t/dataset-custom-property-on-udt-has-value-of-unknown-type-when-written/66022 "2022-11-02T18:55:26Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![bschroeder](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/bschroeder/32/13260_2.png) [@bschroeder](https://forum.inductiveautomation.com/u/bschroeder)\
**Post date:** [November 2, 2022, 6:55pm UTC](https://forum.inductiveautomation.com/t/dataset-custom-property-on-udt-has-value-of-unknown-type-when-written/66022/1 "2022-11-02T18:55:26Z")

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I've got a UDT that we are wanting to attach a DataSet custom property to the main UDT. This will hold static data throughout the UDT and we are trying to get away from having tags just for this purpose.

If I create an instance of this UDT and look at the custom properties I see the normal view for a dataset.

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/2/d/2de99f0c869b8c5e9d597707ae4c8f37b23fdae8.png)

However, if I write to that dataset from anything, scripting, binding etc... the value changes to this:

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/5/7/575932f98b0b12a80c9b6a086a85d49a48e7e1f7.png)

Interestingly the added row is there in the binding and all the data works. I just can't view it from the Tag Browser.

If I create a normal memory tag ad add that same dataset as a custom property on the tag it works just fine. Adding,removing etc all show normally and show the dataset value in the tag browser.

So before I commit to using custom properties for this... is the DataSet value showing [Unknown Value] a bug or am I doing something that is out of bounds for these custom properties?

Edit:  
FWIW this happens in 8.1.20 and 8.1.21

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<div class="post-metadata">

**Author:** ![paul-griffith](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/paul-griffith/32/37249_2.png) [@paul-griffith](https://forum.inductiveautomation.com/u/paul-griffith)\
**Post date:** [November 2, 2022, 8:59pm UTC](https://forum.inductiveautomation.com/t/dataset-custom-property-on-udt-has-value-of-unknown-type-when-written/66022/2 "2022-11-02T20:59:44Z")

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It certainly seems like you should be able to use Dataset just fine in a custom property, so I would say this is a bug.

Does Document have the same issue, out of curiousity?

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<div class="post-metadata">

**Author:** ![bschroeder](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/bschroeder/32/13260_2.png) [@bschroeder](https://forum.inductiveautomation.com/u/bschroeder)\
**Post date:** [November 2, 2022, 9:02pm UTC](https://forum.inductiveautomation.com/t/dataset-custom-property-on-udt-has-value-of-unknown-type-when-written/66022/3 "2022-11-02T21:02:50Z")

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that might be a bit tougher to test with bindings as I'm all in Vision right now. But I'll see what I can do.