Report Builder Unable to retrive workgroups or datasets from Powerbi error: 407 Proxy Authentication

Hi All,

I am getting a consistent error when trying to connect the Report Builder to the a publish dataset. below is the error message i am getting.

Microsoft.ReportBuilder.Diagnostics.ErrorHandling.ReportBuilderException: Le serveur distant a retourné une erreur : (407) Authentification proxy requise. ---> System.Net.WebException: Le serveur distant a retourné une erreur : (407) Authentification proxy requise.
à System.Net.HttpWebRequest.EndGetResponse(IAsyncResult asyncResult)
à System.Net.Http.HttpClientHandler.GetResponseCallback(IAsyncResult ar)

I saw on a post this solution that I tried but it still doesn't work : i added in the file PowerBIReportBuilder.exe.config this code 

<system.net>
<defaultProxy useDefaultCredentials="true"></defaultProxy>
</system.net>

Looks like a proxy issue? Anyone can help me to troubleshoot this issue.

Thanks.