validating radiobutton in winform doesnt work

I followed this example to validate my 2 textboxes:
http://devcenter.infragistics.com/Articles/ArticleTemplate.Aspx?ArticleID=1263

I have 2 radiobuttons, I have them in a panel. User must select a radiobutton. Otherwise, they should get a msg like that example. Not sure why it doesnt work. I clicked on the "events" and added the event. My code is like this. I have an errorProvider. I even set the debugger, clicked OK and the validating event didnt trigger...

private void rbIBM_Validating(object sender, CancelEventArgs e)
        {
            if (!rbSQL.Checked & !rbIBM.Checked)
            {
                errorProvider1.SetError((Control)sender, "Please choose a System");
 
            }
            else
            {
                errorProvider1.Clear();
            }
 
        }

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