Issue with "Get" message with gmail api v1 (Net) - vb.net

Question

Im trying to get info of a gmail message in a datagridview but only returns the datagridview empty (even when I erase the "return nothing" line) but when I try in apis-explorer I get the 200 ok response. What am I doing wrong?
The code Im using is from the google developers documentation:
Imports Google.Apis.Auth.OAuth2
Imports Google.Apis.Services
Imports Google.Apis.Tasks.v1
Imports Google.Apis.Tasks.v1.Data.Tasks
Imports Google.Apis.Tasks.v1.Data
Imports System.Collections.Generic
Imports Google.Apis.Util.Store
Imports System.Threading
Imports System
Imports Google.Apis.Gmail.v1
Imports Google.Apis.Gmail.v1.Data
Public Class Form1
Dim Secrets = New ClientSecrets()
Dim scope = New List(Of String)
Dim initializer = New BaseClientService.Initializer
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Secrets.ClientId = "CLIENT_ID"
Secrets.ClientSecret = "CLIENT_SECRET"
End Sub
Public Shared Function GetMessage(service As GmailService, userId As [String], messageId As [String]) As Message
Try
Return service.Users.Messages.Get(userId, messageId).Execute()
Catch ex As Exception
MsgBox(ex.ToString)
End Try
'Return Nothing
End Function
Private Sub Button14_Click(sender As Object, e As EventArgs) Handles Button14.Click
Dim userId As String = "GMAIL ACCOUNT"
Dim messageId As String = "MESSAGE ID"
Try
scope.Add(GmailService.Scope.MailGoogleCom)
Dim credential = GoogleWebAuthorizationBroker.AuthorizeAsync(Secrets, scope, "XXXXXXXXXXXX#developer.gserviceaccount.google.com", CancellationToken.None).Result()
initializer.HttpClientInitializer = credential
initializer.ApplicationName = "APP NAME"
Dim service = New GmailService(initializer)
Me.DataGridView1.DataSource = GetMessage(service, userId, messageId)
Catch ex As Exception
MsgBox(ex.ToString)
End Try
End Sub
End Class

Answer 1

Thanks Eric but I already solved making some changes. I hope this helps other people because the google developers documentation its not too clear
Imports Google.Apis.Auth.OAuth2
Imports Google.Apis.Services
Imports System.Collections.Generic
Imports Google.Apis.Util.Store
Imports System.Threading
Imports System
Imports Google.Apis.Gmail.v1
Imports Google.Apis.Gmail.v1.Data
Public Class Form1
Dim Secrets = New ClientSecrets()
Dim scope = New List(Of String)
Dim initializer = New BaseClientService.Initializer
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Secrets.ClientId = "CLIENT ID"
Secrets.ClientSecret = "CLIENT SECRET"
End Sub
Public Shared Function GetMessage(service As GmailService, userId As [String], messageId As [String]) As Message
Try
Return service.Users.Messages.Get(userId, messageId).Execute
Catch ex As Exception
MsgBox(ex.ToString)
End Try
Return Nothing
End Function
Private Sub Button14_Click(sender As Object, e As EventArgs) Handles Button14.Click
Try
scope.Add(GmailService.Scope.MailGoogleCom)
Dim credential = GoogleWebAuthorizationBroker.AuthorizeAsync(Secrets, scope, "XXXXXXXXXXXXX#developer.gserviceaccount.google.com", CancellationToken.None).Result()
initializer.HttpClientInitializer = credential
initializer.ApplicationName = "APP NAME"
Dim service = New GmailService(initializer)
Dim userId As String = "EMAIL"
Dim messageId As String = "MESSAGE ID"
Me.DataGridView1.DataSource = GetMessage(service, userId, messageId).Payload.Headers
TextBox1.Text = (GetMessage(service, userId, messageId).Snippet)
Catch ex As Exception
MsgBox(ex.ToString)
End Try
End Sub
End Class