I have done with RNGSERVICEPROVIDER, is it correct?

  Public Sub secrand()
        Static r As Random = Nothing

        If r Is Nothing Then
            Dim seed() As Byte = New Byte(4) {}
            Dim rng As New RNGCryptoServiceProvider
            rng.GetBytes(seed)
            r = New Random(BitConverter.ToInt32(seed, 0))
            Label4.Text = r.Next(1000, 9999)
        End If
    End Sub