# Why I can't write to a tag?

**URL:** <https://forum.inductiveautomation.com/t/why-i-cant-write-to-a-tag/15799>\
**Category:** Ignition\
**Tags:** ignition79\
**Created:** [October 27, 2017, 7:31pm UTC](https://forum.inductiveautomation.com/t/why-i-cant-write-to-a-tag/15799 "2017-10-27T19:31:00Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![jadachi](https://avatars.discourse-cdn.com/v4/letter/j/ee7513/32.png) [@jadachi](https://forum.inductiveautomation.com/u/jadachi)\
**Post date:** [October 27, 2017, 7:31pm UTC](https://forum.inductiveautomation.com/t/why-i-cant-write-to-a-tag/15799/1 "2017-10-27T19:31:00Z")

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Hello, I’m using a Tab Strip component to navigate between various windows, and I want to reflect the selected window in a label on other Window. I’m trying to pass this value (TabStrip.SelectedTab) to a memory tag, and then asign this tag to the label’s text.  
I’m doing this by scripting, in the “Set Tag’s Value” tab, but when I run the program and try this, an error message pops up, and doesn’t let me do this. Why is this happening? Thanks.

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**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:** [October 27, 2017, 8:59pm UTC](https://forum.inductiveautomation.com/t/why-i-cant-write-to-a-tag/15799/2 "2017-10-27T20:59:08Z")

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What’s the text of the error message? Go to the ‘Details’ tab and copy the full trace of the error message, then paste it in here inside three literal ‘grave’ characters: ```

```auto

```

error

```auto

```