Translate Curl's --key and --cert to VB.NET - vb.net

Question

I need to post via VB.NET two files, a key file and a pem file, this can be done via Curl with the command:
curl https://someWebSite.com/test --key ./private_key.key --cert ./certificate.pem -d grant_type=password -d username="" -d password=""
So far I've done this in VB.NET but it just pops an error that says "Additional information: The remote server returned an error: (401) Unauthorized.
i reached one example where they use a *.p12 file and i tried to recreate it in VB.NET but still saying the same error. This is my Code:
Dim token As String = ""
Dim uriVar As New Uri("https://someWebSite.com/test")
Dim user As String = ""
Dim password As String = ""
Dim request As HttpWebRequest = CType(WebRequest.Create(uriVar), HttpWebRequest)
request.KeepAlive = False
request.ProtocolVersion = HttpVersion.Version11
request.Method = "POST"
Dim credential As New NetworkCredential(user, password)
request.Credentials = credential
Dim keystoreFileName As String = "keystore.p12"
Dim pathCert As String = Path.Combine(Environment.CurrentDirectory, "cert\", keystoreFileName)
Dim cert As New X509Certificate(pathCert, "allpassword")
request.ClientCertificates.Add(cert)
request.ContentType = "application/x-www-form-urlencoded"
request.ContentLength = 39
request.Accept = "*/*"
Dim requestStream As Stream = request.GetRequestStream()
Dim post_data As String = "grant_type=password&username=&password="
Dim postBytes As Byte() = Encoding.ASCII.GetBytes(post_data)
requestStream.Write(postBytes, 0, postBytes.Length)
requestStream.Close()
Dim response As HttpWebResponse = CType(request.GetResponse(), HttpWebResponse) 'Here pops the error...
Dim responseJson = New StreamReader(response.GetResponseStream()).ReadToEnd()
Return responseJson