# Issue with my calibration

**URL:** <https://forum.pioreactor.com/t/issue-with-my-calibration/1264>\
**Category:** API & Data Access\
**Created:** [October 21, 2026, 9:19am UTC](https://forum.pioreactor.com/t/issue-with-my-calibration/1264 "2026-10-21T09:19:39Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![honorex](https://forum.pioreactor.com/letter_avatar_proxy/v4/letter/h/c37758/32.png) [@honorex](https://forum.pioreactor.com/u/honorex)\
**Post date:** [October 21, 2026, 9:19am UTC](https://forum.pioreactor.com/t/issue-with-my-calibration/1264/1 "2026-10-21T09:19:39Z")

</div>

Hello everybody,

I tried calibrating the OD reading from the Pioreactor to that of the 600nm spectrophotometer. But after following the protocol and entering my data (ranging from 0.04 to 2.024, in 7 dilutions), in ascending and descending order, I can’t get a graph calibrated to the new values, and I don’t even know if the calibration worked because the same values ​​appear in the SSH. Furthermore, I thought I probably needed more dilutions, so I did 16 this time, and after validating, the website displays: “Unable to find calibration data,” even though the graph appeared just before.  
Furthermore, the DO reading in the Pioreactors section does not start if calibration is active; however, it appears to remain active if it was started before calibration began. Is this normal, and how can I know if it is working?  
And when I take a look to the YAML, I see, in the coefficient side, some minus signe in red, does this affect the problem ?

---

<div class="post-metadata">

**Author:** ![CamDavidsonPilon](https://forum.pioreactor.com/user_avatar/forum.pioreactor.com/camdavidsonpilon/32/3_2.png) [@CamDavidsonPilon](https://forum.pioreactor.com/u/CamDavidsonPilon)\
**Post date:** [October 22, 2026, 5:12pm UTC](https://forum.pioreactor.com/t/issue-with-my-calibration/1264/3 "2026-10-22T17:12:02Z")

</div>

Hi @honorex,

> [@honorex](#):
>
> Furthermore, I thought I probably needed more dilutions, so I did 16 this time, and after validating, the website displays: “Unable to find calibration data,” even though the graph appeared just before.

This _may_ be a bug in the UI, where some values like `#`, `?` or `%` are encoded properly, so an error is returned. This will be fixed in the next release.

> Furthermore, the DO reading in the Pioreactors section does not start if calibration is active;

Do you have an OD-blank - if so, try removing that first.

> And when I take a look to the YAML, I see, in the coefficient side, some minus signe in red, does this affect the problem ?

I think this is okay, but maybe provide some screenshots?

* * *

We have some other OD calibration fixes (and a better calibration experience) in the next software release - coming soon.