What i say is followed by wether or not it works. [Yes = Works, No = Doesnt.]
I'm trying to make it so that:
If checkbox1 and checkbox2 are both checked, a msg box comes up. [yes]
If textbox4 is empty a msg box comes up. [yes]
If textbox5 is empty a msg box comes up. [yes]
If neither checkbox1 or checkbox2 are checked, a msg comes up. [yes]
If any of these errors are found, msg box comes up asking to fix errors. [no]

My code:
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        If ((CheckBox1.Checked) And (CheckBox2.Checked)) Then
            MsgBox("Error: How can you possibly be both the Money and Item Sender?", MsgBoxStyle.Critical)
        End If
        If TextBox4.Text = "" Then
            MsgBox("Error: Please include your Steam ID!", MsgBoxStyle.Critical)
        End If
        If TextBox5.Text = "" Then
            MsgBox("Error: Please include their Steam ID", MsgBoxStyle.Critical)
        End If
        If ((Not CheckBox1.Checked) And (Not CheckBox2.Checked)) Then
            MsgBox("Error: Please select a trade role.", MsgBoxStyle.Critical)
        End If
        If (Not ((CheckBox1.Checked) And (CheckBox2.Checked))) + (Not TextBox4.Text = "") + (Not TextBox5.Text = "") + (Not ((Not CheckBox1.Checked) And (Not CheckBox2.Checked))) Then
            Dim oForm As Form3

            oForm = New Form3()


            oForm = Nothing

            MsgBox("Please fix errors.", MsgBoxStyle.Information)
        End If
    End Sub