From a news release:
Northwest Arkansas (January 9, 2013) – Walton Arts Center regrets to announce that due to recent illness and under doctor's orders, Ronnie Milsap must cancel his upcoming show at Walton Arts Center on Sunday, January 12. Ronnie extends his sincere apologies to the fans and hopes to return to the road very soon.
There are no plans to reschedule at this time. Ticket holders will be contacted directly by the box office with options to donate the value of the tickets, exchange into another performance or receive a full refund.