VB.Net Function does not inherit textbox values from another class

Question

I'm programming in a MVVM pattern and I have problems using textbox values in my function. When I call my function it does not use the values the user entered in the textbox. It is just empty. I looks like it inherits empty fields and just skips the filled in textbox fields. Please take a look at my code here

I call the addUser function from the AccountAddView here

Public Class AccountaddView
    Public Sub btnAccountAdd_Click(sender As Object, e As RoutedEventArgs) Handles btnAccountAdd.Click

        If txtPasswordAdd.Password <> txtPasswordAdd2.Password Then
            warningLabel.Visibility = Visibility.Visible

        Else

            Dim model = New AccountaddModel()
            model.addUser()

The functions triggers the Model

Public Class AccountaddModel
Inherits AccountaddViewModel

Public Function addUser()
    Dim url As String = "https://azurefunctionsmywebsite" + "&name=" + username + "&pass=" + pass + "&role=" + role
    Dim request As WebRequest = WebRequest.Create(url)
    Dim response As WebResponse = request.GetResponse()
    Dim result As String = New StreamReader(response.GetResponseStream()).ReadToEnd()
End Function
End Class

As you can see the Model inherits from the AccountAddViewModel. This class stores the variables that the user filled in the textbox

Public Class AccountaddViewModel
    Inherits AccountaddView

    Public username As String = txtUsernameAdd.Text
    Public pass As String = txtPasswordAdd.Password
    Public role As String = txtProjectrolAdd.Text
End Class

I have no errors. When I fill in the username,pass and role as an user the URL in the function does not fill it with the data. It is just empty.

I hope someone can help me out with this inheritance issue.