# Interpolation does not work correctly in Easy Chart and "system.tag.queryTagCalculations()"

**URL:** <https://forum.inductiveautomation.com/t/interpolation-does-not-work-correctly-in-easy-chart-and-system-tag-querytagcalculations/40701>\
**Category:** Ignition\
**Tags:** ignition80\
**Created:** [November 16, 2020, 6:06pm UTC](https://forum.inductiveautomation.com/t/interpolation-does-not-work-correctly-in-easy-chart-and-system-tag-querytagcalculations/40701 "2020-11-16T18:06:39Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![informatica](https://avatars.discourse-cdn.com/v4/letter/i/3ab097/32.png) [@informatica](https://forum.inductiveautomation.com/u/informatica)\
**Post date:** [November 16, 2020, 6:06pm UTC](https://forum.inductiveautomation.com/t/interpolation-does-not-work-correctly-in-easy-chart-and-system-tag-querytagcalculations/40701/1 "2020-11-16T18:06:39Z")

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Good afternoon.

In Ignition **8.0.14** , I have configured a tag to **history** with this Tag Group (Scan Class):

![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/7/4/7430bb02b30911036693d9e71b434645d99e519b.png)

When I query the tag with “_**system.tag.queryTagCalculations()**_” to know its “_ **DurationOff** _”, the function returns **fewer seconds if I ask from 6 AM to 13 PM than when I ask from 6 AM to 10 AM, for the same date**. This doesn’t make sense and is very **confusing**.

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/3/a/3a8b7cb67e37f40818f5f3ad4e266836d425b062.png)

Something similar happens with “_ **Easy Chart** _”. One interval shows the **value 0** from 6 to 10 and the other interval **has no value** from 6 to 10:

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/9/8/98ac1d2b40540871d1603b5670c26b0eea0eded0.png)

* * *

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/4/b/4b4fee5740e2b96cb88d697b123b7db0a2e0b570.png)

Best Regards.