Public Class Form1
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
        Form2.Show()
    End Sub
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button2.Click
        Dim str As String = R_Strasse
        Label1.Text = R_Strasse
    End Sub
End Class

Public Class Form2
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
        Form1.Show()
        Me.Close()
    End Sub
End Class

Module Module1
    Public R_Strasse As String = String.Empty
End Module