Update Shared Datasouce for Report using PowerShell

Hello,

We are in the process of migrating from SSRS to PBI-RS and have been testing reports in DEV using DEV Datasources.  We have over 300 reports, that we need to switch to Production Datasources, and I've been looking for a way to do it via powershell.. As a NOOB, I'm running into issues.   I downloaded the ReportingServicesTools and it looked like it would be pretty simple... NOPE...   I found that I should be using the Get-RSITEMDatasource and Set-RSITEMDatasource based on  my reading.. so I Ran the following:

PS C:\> $dataSources = Get-RsItemDataSource -ReportServerUri 'http://powerbi.dev.sql.odnss.com/Reportserver/' -RsItem '/docket/All Timekeepers'

Ran Succesfully

Then I ran

PS C:\> Set-RsItemDataSource -DataSource $datasources -RsItem '/AR/AR Aging' -ReportServerUri 'http://powerbi.dev.sql.odnss.com/reportserver/'

I get the error below

Please use Set-RsDataSource to update shared data sources!
At C:\Program Files\WindowsPowerShell\Modules\ReportingServicesTools\0.0.5.0\Functions\CatalogItems\Set-RsItemDataSource.ps1:143 char:17
+ ... throw "Please use Set-RsDataSource to update shared data ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : OperationStopped: (Please use Set-...d data sources!:String) [], RuntimeException
+ FullyQualifiedErrorId : Please use Set-RsDataSource to update shared data sources!

I'm not trying to update the Shared Datasource itself... I'm simply tying to update the report to use another Shared Datasouce.. 

What am I doing wrong?