VB Programs - Prime or not

Public Class Form1

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim I, N As Integer
        N = CInt(TextBox1.Text)
        For I = 2 To N - 1
            If N Mod I = 0 Then
                Label2.Text = "THE NUMBER IS NOT A PRIME NUMBER"
                Exit Sub
            End If
        Next I
        Label2.Text = "THE NUMBER IS A PRIME NUMBER"
    End Sub

End Class