# \[Solved\]I can't use some function after I download and test app

**URL:** <https://community.thunkable.com/t/solved-i-cant-use-some-function-after-i-download-and-test-app/1273948>\
**Category:** Questions about Thunkable X\
**Tags:** solved, download\
**Created:** [May 10, 2021, 12:19pm UTC](https://community.thunkable.com/t/solved-i-cant-use-some-function-after-i-download-and-test-app/1273948 "2021-05-10T12:19:57Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![fanfan4204b7r2n](https://avatars.discourse-cdn.com/v4/letter/f/4491bb/32.png) [@fanfan4204b7r2n](https://community.thunkable.com/u/fanfan4204b7r2n)\
**Post date:** [May 10, 2021, 12:19pm UTC](https://community.thunkable.com/t/solved-i-cant-use-some-function-after-i-download-and-test-app/1273948/1 "2021-05-10T12:19:57Z")

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I use store variable to set as a list to store some text. This function works normally in App preview, but it doesn’t work after downloading it as an ipa file. How can I solve it?

I have tried updating the software and restarting the phone, but these are useless.

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**Author:** ![muneer](https://sea1.discourse-cdn.com/flex015/user_avatar/community.thunkable.com/muneer/32/75210_2.png) [@muneer](https://community.thunkable.com/u/muneer)\
**Post date:** [May 10, 2021, 12:40pm UTC](https://community.thunkable.com/t/solved-i-cant-use-some-function-after-i-download-and-test-app/1273948/2 "2021-05-10T12:40:46Z")

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When using `stored variables` you need to check if it is **null** before attempting to add entries to the list. When you install the app in a new device the `stored variable` is **null** and therefore will fail to add to the list.

Best practice is to check your `stored variable` when starting the app and if **= null** then initialize to the appropriate value such as` empty list` in your case then you can use it in a normal way.

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**Author:** ![backscratcher2007](https://sea1.discourse-cdn.com/flex015/user_avatar/community.thunkable.com/backscratcher2007/32/104623_2.png) [@backscratcher2007](https://community.thunkable.com/u/backscratcher2007)\
**Post date:** [May 10, 2021, 1:01pm UTC](https://community.thunkable.com/t/solved-i-cant-use-some-function-after-i-download-and-test-app/1273948/3 "2021-05-10T13:01:40Z")

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There was a topic like this created just a few minutes ago ,check it out [How do I use Google Sheets on a device?](https://community.thunkable.com/t/how-do-i-use-google-sheets-on-a-device/1273924)

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**Author:** ![fanfan4204b7r2n](https://avatars.discourse-cdn.com/v4/letter/f/4491bb/32.png) [@fanfan4204b7r2n](https://community.thunkable.com/u/fanfan4204b7r2n)\
**Post date:** [May 11, 2021, 2:12pm UTC](https://community.thunkable.com/t/solved-i-cant-use-some-function-after-i-download-and-test-app/1273948/4 "2021-05-11T14:12:00Z")

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Thanks for helping!

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**Author:** ![ioannis](https://sea1.discourse-cdn.com/flex015/user_avatar/community.thunkable.com/ioannis/32/146956_2.png) [@ioannis](https://community.thunkable.com/u/ioannis)\
**Post date:** [November 8, 2024, 1:22pm UTC](https://community.thunkable.com/t/solved-i-cant-use-some-function-after-i-download-and-test-app/1273948/5 "2024-11-08T13:22:38Z")

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