# Start trace does not save my probe location selection
**URL:** https://discourse.paraview.org/t/start-trace-does-not-save-my-probe-location-selection/7962
**Category:** ParaView Support
**Created:** [September 9, 2021, 8:33am UTC](https://discourse.paraview.org/t/start-trace-does-not-save-my-probe-location-selection/7962 "2021-09-09T08:33:55Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@babouletatou](https://discourse.paraview.org/u/babouletatou)
#### Post date: [September 9, 2021, 8:33am UTC](https://discourse.paraview.org/t/start-trace-does-not-save-my-probe-location-selection/7962/1 "2021-09-09T08:33:55Z")
Hi, so I would like to have some help about this problem:
I’d like to create a macro which could give me the pressure using **probe location** , but even if during _start trace_ I do select the **probe location** point to give me the pressure over time, when I run the macro, paraview displays an empty graph because nothing is selected in the **PlotSelectionOverTime** filter.
Thank’s for your help!
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### Author:  [@babouletatou](https://discourse.paraview.org/u/babouletatou)
#### Post date: [September 13, 2021, 9:28am UTC](https://discourse.paraview.org/t/start-trace-does-not-save-my-probe-location-selection/7962/2 "2021-09-13T09:28:21Z")
Up
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [September 14, 2021, 10:31am UTC](https://discourse.paraview.org/t/start-trace-does-not-save-my-probe-location-selection/7962/3 "2021-09-14T10:31:11Z")
please add clear steps to reproduce
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### Author:  [@babouletatou](https://discourse.paraview.org/u/babouletatou)
#### Post date: [September 14, 2021, 2:59pm UTC](https://discourse.paraview.org/t/start-trace-does-not-save-my-probe-location-selection/7962/5 "2021-09-14T14:59:58Z")
Ok, so:
Firstly, I _Start Trace_,
Then I open my dataset which is a group: data for each time step.
I create a **probe location** and I select the point as follows:
**→**
Finally I **plot selection over time** and select the pressure.
The matter is that something appear when I do it manually but when I use the script thanks to the _Trace_, the selection of **plotselectionovertime** remains empty:
_Manually_:
_With the trace_:
However I had a look on the script and a process ID (-1,0) is mentionned, so I don’t understand why it’s not selected at the end
Thanks for your help
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [September 14, 2021, 3:00pm UTC](https://discourse.paraview.org/t/start-trace-does-not-save-my-probe-location-selection/7962/6 "2021-09-14T15:00:22Z")
The trace seems to miss a CreateSelection python calls. You should be able to add it yourself in your python script.
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### Author:  [@babouletatou](https://discourse.paraview.org/u/babouletatou)
#### Post date: [September 14, 2021, 3:21pm UTC](https://discourse.paraview.org/t/start-trace-does-not-save-my-probe-location-selection/7962/7 "2021-09-14T15:21:10Z")
Thank you for your answer,
I was looking for this function, but it seems like it doesn’t exist, either on the paraview documentation where I can’t find how it works or in paraview python shell (When I write CreateSe… it doesn’t suggest me anything).
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [September 15, 2021, 9:31am UTC](https://discourse.paraview.org/t/start-trace-does-not-save-my-probe-location-selection/7962/8 "2021-09-15T09:31:46Z")
[https://docs.paraview.org/en/latest/UsersGuide/selectingData.html#creating-selections-in-python](https://docs.paraview.org/en/latest/UsersGuide/selectingData.html#creating-selections-in-python)