Alison Krauss canceled a Thursday night (Feb. 21) appearance with vocalist Bobby McFerrin and bassist Edgar Meyer at New York's Carnegie Hall because of an undisclosed illness, according to a spokesperson for the venue. The event is part of McFerrin's Perspectives series of themed concerts at Carnegie Hall. His future collaborators in the series include Yo-Yo Ma and jazz greats Chick Corea and Jack DeJohnette. Mandolinist Sierra Hull and guitarist-banjoist Ron Block, who were scheduled to appear Thursday as part of Krauss' band, will still perform with McFerrin and Meyer. Krauss' tour with Robert Plant is scheduled to begin April 19 in Louisville, Ky.