[Microsoft.IdentityModel.Clients.ActiveDirectory.AuthenticationContex] does not contain a method named ‘AcquireToken’.

Hey,

I try to work with Azure AD. 

# Change to
correct file location

Add-Type
-Path
"D:\GraphAPI\Microsoft.IdentityModel.Clients.ActiveDirectory.3.10.305161347\lib\net45\Microsoft.IdentityModel.Clients.ActiveDirectory.dll" 

# Change
these three values to your application and tenant settings

$clientID =
"# CLIENT ID for application”

$clientSecret
= " # KEY for application”

$tenant =
" # The tenant domain name”

 

$resAzureGraphAPI
= "https://graph.windows.net";

$serviceRootURL
= "https://graph.windows.net/$tenant"

$authString
= "https://login.windows.net/$tenant";  [Microsoft.IdentityModel.Clients.ActiveDirectory.AuthenticationContext]$AuthContext
=
[Microsoft.IdentityModel.Clients.ActiveDirectory.AuthenticationContext]$authString 

[Microsoft.IdentityModel.Clients.ActiveDirectory.ClientCredential]$clientCredential
= New-Object -TypeName
"Microsoft.IdentityModel.Clients.ActiveDirectory.ClientCredential"($clientID,
$clientSecret) 

# Requests
a bearer token

$authenticationResult
= $AuthContext.AcquireToken($resAzureGraphAPI, $clientCredential);

Here I get the error: Method invocation failed because [Microsoft.IdentityModel.Clients.ActiveDirectory.AuthenticationContex] does not contain  a method named ‘AcquireToken’.

What can I do to solve this error?

Thanks for your help

Stefan