417 Expectation Failed on tableau restapi powershell script

Question

I'm new to powershell and trying to make REST API calls to tableau server (version 2018.1) using powershell version 5.1, but I'm getting an issue that I can't seem to fix. The code I'm sending is as follows:

 #Variables:
$sites = 'site'
$APiversion = '3.0'
$DeployPassword = 'Password123'
$DeployUser = 'Defaultuser'
$Tableauservername = 'servername'

# generate body for sign in
$signin_body = (’<tsRequest>
 <credentials name=“’ + $DeployUser + ’” password=“’+ $DeployPassword + ’” >
   <site contentUrl=“” />
 </credentials>
</tsRequest>’)
#[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
$response = Invoke-RestMethod -Uri https://$Tableauservername/api/3.0/auth/signin -Body $signin_body -Method post -UseBasicParsing

The following error notice appears:

tion given in the Expect request-header
field could not be met by this server.
The client sent
    Expect: 100-continue

Only the 100-continue expectation is supported.


At line:16 char:13
+ $response = Invoke-RestMethod -Uri https://$Tableauservername/api/3.0 ...
+             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (System.Net.HttpWebRequest:HttpWebRequest) [Invoke-RestMethod], WebException
    + FullyQualifiedErrorId : WebCmdletWebResponseException,Microsoft.PowerShell.Commands.InvokeRestMethodCommand

Is there anyone who can tell me what I'm doing wrong here?

I've tried changing the formatting of the quotations and such, but it doesn't appear to work.