Delegate tutorial vb.net

Public Class Form1
    Delegate Sub SubStr(ByVal str As String)

    Protected Sub DelegTest()
        Dim FRM As New Form2
        Dim SStr As SubStr = AddressOf FRM.TestCls
        SStr.Invoke("Delegate Run")
    End Sub

    Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        DelegTest()
    End Sub
End Class

Public Class Form2

    Public Sub TestCls(ByVal str As String)

        MsgBox(str)

    End Sub

End Class