Updating connection String of power bi reports using powerShell

[Syrine]

Hello, 

I am writing a powerShell Script using the module ReportingServicesTools to automate updating the connection Strings of my PowerBi Reports deployed on PowerBi Report Server. The Script works fine untill the last line which makes the updates on the report server using the function Set-RsRestItemDataSource. The Error is 400 Incorrect Demand. 

All the Echos return what I expect with no problem.

Here is my Script : 

and my Error : 

Part of the error is written in French and it says " the server returned an erreur : 400 incorrect demande ".

What I hid in blue is the name of my report.

I looked at this link : https://community.powerbi.com/t5/Service/Update-connection-string-via-API/m-p/1850500#M128979 and on the Internet but nothing helped my case.

I am using this version of PowerBi Report server : 

and I followed the official Docs : https://learn.microsoft.com/en-us/power-bi/report-server/connect-data-source-apis-pre-oct-2020

I tried another Script with this version of the Docs too but it didn't work for me : https://learn.microsoft.com/en-us/power-bi/report-server/connect-data-source-apis

I would be glad if you could help me!