远程服务器返回错误：（407）Windows应用程序

Question

在运行下面的代码时我得到了＃34;远程服务器返回了一个错误：（407）需要代理验证。＆＃34;问题。我做了很多RND，但仍面临同样的问题...

代码：

Private Sub btnDownload_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDownload.Click
    Application.DoEvents()
    Dim web_client As WebClient = New WebClient
    Try
        web_client.UseDefaultCredentials = True

        web_client.DownloadFile(txtRemoteFile.Text, txtLocalFile.Text)
        MessageBox.Show("Done")

    Catch ex As Exception
        Dim wp As WebProxy
        wp = New WebProxy("ProxyIP", ProxyPort)
        wp.Credentials = New NetworkCredential("LoginName", "Password", "DomainName")
        web_client.Proxy = wp
        web_client.DownloadFile(txtRemoteFile.Text, txtLocalFile.Text)
        MessageBox.Show("Done")
    End Try

End Sub

提前致谢...