VB.net set folder of FolderBrowserDialog1 to "My Documents"

Hi
I get the error "Conversion from string to integer not valid" at the line marked 'ERROR
         Dim result As DialogResult
            With Me.FolderBrowserDialog1
                .ShowDialog()
                .RootFolder = System.Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments) 'ERROR
     
            End With