# Help with Perspective Expression

**URL:** <https://forum.inductiveautomation.com/t/help-with-perspective-expression/75701>\
**Category:** Ignition\
**Tags:** perspective\
**Created:** [June 29, 2023, 12:58pm UTC](https://forum.inductiveautomation.com/t/help-with-perspective-expression/75701 "2023-06-29T12:58:25Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Jordan\_Saneholtz](https://avatars.discourse-cdn.com/v4/letter/j/e9c0ed/32.png) [@Jordan\_Saneholtz](https://forum.inductiveautomation.com/u/Jordan_Saneholtz)\
**Post date:** [June 29, 2023, 12:58pm UTC](https://forum.inductiveautomation.com/t/help-with-perspective-expression/75701/1 "2023-06-29T12:58:25Z")

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I obviously have an error in my expression binding but am I struggling to figure out where. Would appreciate a second set of more seasoned eyes.

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/2/4/249dcdb8104a284375fb327aaef56fd2546c1a56.png)  
 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/9/7/97a10f4fc554a86f6af054ed81b51c841c5c7172.png)

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**Author:** ![deon.korb](https://avatars.discourse-cdn.com/v4/letter/d/8c91f0/32.png) [@deon.korb](https://forum.inductiveautomation.com/u/deon.korb)\
**Post date:** [June 29, 2023, 1:01pm UTC](https://forum.inductiveautomation.com/t/help-with-perspective-expression/75701/2 "2023-06-29T13:01:43Z")

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You can see the error detail if you hover over the error message in the bottom left corner.

I suspect it is caused by the capitalisation of the `tag()` expression function.

Also, consider using a tag binding to a custom property and then using those custom properties in your expression binding. Easier to troubleshoot and I believe also more performant than `tag()`.

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<div class="post-metadata">

**Author:** ![Jordan\_Saneholtz](https://avatars.discourse-cdn.com/v4/letter/j/e9c0ed/32.png) [@Jordan\_Saneholtz](https://forum.inductiveautomation.com/u/Jordan_Saneholtz)\
**Post date:** [June 29, 2023, 1:33pm UTC](https://forum.inductiveautomation.com/t/help-with-perspective-expression/75701/3 "2023-06-29T13:33:21Z")

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First off thanks for the help, I was not aware of the hover feature so much appreciated. Secondly in theory I understand how to tag bind to a custom property but I guess I'm not sure how and where to implement it here. Could you possibly provide a little more detail on this.

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<div class="post-metadata">

**Author:** ![deon.korb](https://avatars.discourse-cdn.com/v4/letter/d/8c91f0/32.png) [@deon.korb](https://forum.inductiveautomation.com/u/deon.korb)\
**Post date:** [June 29, 2023, 1:40pm UTC](https://forum.inductiveautomation.com/t/help-with-perspective-expression/75701/4 "2023-06-29T13:40:52Z")

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First, create some custom properties, one for each of those tags you reference:  
[Perspective Component Properties - Ignition User Manual 8.1 - Ignition Documentation (inductiveautomation.com)](https://docs.inductiveautomation.com/display/DOC81/Perspective+Component+Properties#PerspectiveComponentProperties-CreatingCustomProperties)

Bind each to the required tag, using your tag path expression:  
[Tag Bindings in Perspective - Ignition User Manual 8.1 - Ignition Documentation (inductiveautomation.com)](https://docs.inductiveautomation.com/display/DOC81/Tag+Bindings+in+Perspective#TagBindingsinPerspective-ExpressionBindingMode)

Then, rather use these custom properties in your style binding shown above:  
[Expression Bindings in Perspective - Ignition User Manual 8.1 - Ignition Documentation (inductiveautomation.com)](https://docs.inductiveautomation.com/display/DOC81/Expression+Bindings+in+Perspective)