Due to a bout with bronchitis, witchy woman Stevie Nicks has cancelled several recent concert appearances. Though it was unspecified in a press release on Monday, the affliction may still have her down, because Nicks has now cancelled her appearance at Riverport Amphitheatre, scheduled for Tuesday night. That's too bad for Nicks' fans, but also for fans of former St. Louisan Sheryl Crow, who helped produce Nicks' most recent album, and was touring alongside the erstwhile Mac mama. Especially disappointing is the fact that the show won't be rescheduled. Tickets must be returned to the original point of purchase for refunds starting at 10 a.m. on Tuesday. For tickets purchased by phone or online, photocopy the tickets for your records and mail the originals to Ticketmaster Customer Service, Re: Cancelled performance, 1000 Corporate Landing, Charleston, WV, 25311. Include your name, address, phone number, and confirmation number. For more information, call 314-421-4400 or 618-222-2900.