Error 500 when I specify tenant with REST API login in Visual studio

I’m using this nuget in visual studio: https://github.com/Acumatica/AcumaticaRESTAPIClientForCSharp/

Trying to set up a very basic bambooHR - Acumatica integration to create leave requests from bamboo as timeEntries in Acumatica.

When I log in with just a username and password, everything works and it logs me into our live tenant. When I use my local offline demo vm I have no tenants to test with also.

I want to log into our test tenant, but when I specify the test tenant and branch I get a Server error 500 - internal server error. 

Has anyone else run into this before?

 In my main program I have:

 myAcumaticaStuff.Login(AcumaticaBaseUrl, "ApiLogin", "******", "Staging", "Edmonton", "en-CA")

The sub in the module:

(myauthApi is from: Imports Acumatica.Auth.Api)

Public Shared Sub Login(siteURL As String, username As String, password As String, Optional tenant As String = Nothing, Optional branch As String = Nothing, Optional locale As String = Nothing)
            myauthApi = New AuthApi(siteURL)

            Try
                Dim loginRequest As New Credentials(username, password, "", tenant, branch, locale)
                myauthApi.LogIn(loginRequest)
                Console.WriteLine("Login successful!")
            Catch ex As ApiException
                Console.WriteLine("An error occurred: " + ex.Message)
            End Try

End Sub

I’ve tried to use the tenant ID instead of its name but I get the same error.