From ABCNews.com:

they were surprised to hear that the “Congress in Your Corner” event to which they had been invited — by a robocall from Kratovil himself — was not to be a public airing of grievances, but instead an opportunity for private, one-on-one sessions with the freshman Democrat. As the crowd grew, and began venting frustration over the fact they would only be meeting with the congressman behind closed doors, Kratovil’s aides suggested he switch to a town hall format.