It's rather poor of "KenCen" to expect visitors wanting to purchase for other events to know what was going to happen today. They did have an advisory sheet, but you had to know to read it.
A couple weeks ago, KenCen moved a Millennium Stage event into the concert hall (Afgahn Naitonal Orchestra) and visitors who did not know to arrive early missed it. There seems to be a problem with advising customers. Maybe you just do need to follow them on Twitter and Facebook -- admit I hadn't done that yet.
An "Apprentice" for Donald Trump would have anticipated this problem and had a separate server or domain set up specifically for this event. Otherwise, "you're fired."
Kennedy Center does not run itself particularly well "as a business". But, again, it's non-profit with heavy government involvement. So that's what you get.
Why doesn't the KC set up a completely separate domain name, or else A-record alias, to process heavy volume?