# Error in expression not being displayed **URL:** \ **Category:** Ignition\ **Created:** [May 11, 2010, 2:36pm UTC](https://forum.inductiveautomation.com/t/error-in-expression-not-being-displayed/1838 "2010-05-11T14:36:53Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![AlThePal](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/althepal/32/3603_2.png) [@AlThePal](https://forum.inductiveautomation.com/u/AlThePal)\ **Post date:** [May 11, 2010, 2:36pm UTC](https://forum.inductiveautomation.com/t/error-in-expression-not-being-displayed/1838/1 "2010-05-11T14:36:53Z")
Say you have tag A and tag B in a folder, with tag A using tag B in an expression. If you move the location of tag B, tag A’s expression now does not evaluate, but no error is shown - it freezes at the last good value. I would have thought it should immediately show a ‘Not\_Found’ error. If you start and stop the Ignition service, it does show a ‘Not\_Found’ error. ---
**Author:** ![Travis.Cox](https://avatars.discourse-cdn.com/v4/letter/t/b9bd4f/32.png) [@Travis.Cox](https://forum.inductiveautomation.com/u/Travis.Cox)\ **Post date:** [May 11, 2010, 4:34pm UTC](https://forum.inductiveautomation.com/t/error-in-expression-not-being-displayed/1838/2 "2010-05-11T16:34:18Z")
Well, it depends on the expression. If the expression cannot evaluate the quality of the tag should be bad. ---
**Author:** ![AlThePal](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/althepal/32/3603_2.png) [@AlThePal](https://forum.inductiveautomation.com/u/AlThePal)\ **Post date:** [May 11, 2010, 4:58pm UTC](https://forum.inductiveautomation.com/t/error-in-expression-not-being-displayed/1838/3 "2010-05-11T16:58:32Z")
It should be, but it isn’t ☹ ---
**Author:** ![Travis.Cox](https://avatars.discourse-cdn.com/v4/letter/t/b9bd4f/32.png) [@Travis.Cox](https://forum.inductiveautomation.com/u/Travis.Cox)\ **Post date:** [May 11, 2010, 4:59pm UTC](https://forum.inductiveautomation.com/t/error-in-expression-not-being-displayed/1838/4 "2010-05-11T16:59:29Z")
What data types are your two tags and what is the expression you are using? ---
**Author:** ![AlThePal](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/althepal/32/3603_2.png) [@AlThePal](https://forum.inductiveautomation.com/u/AlThePal)\ **Post date:** [May 11, 2010, 5:03pm UTC](https://forum.inductiveautomation.com/t/error-in-expression-not-being-displayed/1838/5 "2010-05-11T17:03:16Z")
Tags are Int4. Expression for ‘Tag A’ is`{[.]Tag B}`If I then move Tag B to another folder, no error is shown for Tag A (its DataQuality is still ‘GOOD\_DATA’). ---
**Author:** ![Travis.Cox](https://avatars.discourse-cdn.com/v4/letter/t/b9bd4f/32.png) [@Travis.Cox](https://forum.inductiveautomation.com/u/Travis.Cox)\ **Post date:** [May 11, 2010, 8:23pm UTC](https://forum.inductiveautomation.com/t/error-in-expression-not-being-displayed/1838/6 "2010-05-11T20:23:16Z")
We have found a bug. When you move the tag to another folder or rename it, it doesn’t cause the expression on Tag A to evaluate again since it is waiting for a value change. If you were to go into Tag A’s expression and just press OK the quality will be NOT\_FOUND. ---
**Author:** ![AlThePal](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/althepal/32/3603_2.png) [@AlThePal](https://forum.inductiveautomation.com/u/AlThePal)\ **Post date:** [May 11, 2010, 9:08pm UTC](https://forum.inductiveautomation.com/t/error-in-expression-not-being-displayed/1838/7 "2010-05-11T21:08:18Z")
When I go into Tag A’s expression and press OK, nothing changes. Its Quality is still GOOD\_DATA, even though the expression is clearly wrong - the reference to Tag B is pointing to the wrong folder. I actually have to change something in the expression before it is re-evaluated. ---
**Author:** ![Travis.Cox](https://avatars.discourse-cdn.com/v4/letter/t/b9bd4f/32.png) [@Travis.Cox](https://forum.inductiveautomation.com/u/Travis.Cox)\ **Post date:** [May 11, 2010, 9:15pm UTC](https://forum.inductiveautomation.com/t/error-in-expression-not-being-displayed/1838/8 "2010-05-11T21:15:58Z")
Right, good point. 🙂