# Binding Errors at Design Time

**URL:** <https://forum.inductiveautomation.com/t/binding-errors-at-design-time/34233>\
**Category:** Ignition\
**Created:** [April 27, 2020, 1:28pm UTC](https://forum.inductiveautomation.com/t/binding-errors-at-design-time/34233 "2020-04-27T13:28:45Z")\
**Posts on this page:** 1\
**Showing post:** 5

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**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\
**Post date:** [October 13, 2021, 2:51pm UTC](https://forum.inductiveautomation.com/t/binding-errors-at-design-time/34233/5 "2021-10-13T14:51:38Z")

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Should be two ampersands. A single is for bitwise `AND`, aka `BAnd`.

The root cause is that tag bindings in a Vision Client don’t have a value when they start–there’s a gateway round-trip that must happen at startup. Expressions must immediately return an answer, so tags are null or sometimes `-1`. The `try()` function is the simplest way to get past the problem.

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