Nebraska athletic ticket officials are warning fans to be careful when buying football tickets. Officials discovered 18 counterfeit tickets were sold on Craigslist for the Sept. 29 game against Wisconsin. People with the invalid tickets were unable to enter Memorial Stadium. UNL police are still investigating. Several other schools around the country have also reported a rise in the distribution of counterfeit tickets. The Cornhuskers play 20th-ranked Michigan in Lincoln on Saturday night. Nebraska Assistant Athletic Director for Ticketing Holly Adam recommends that fans know who the seller is before buying tickets from an outside source. Fans with questions about ticket availability for football or any other Nebraska athletic event should contact the Nebraska Athletic Ticket Office at 1-800-8-BIG RED or 402-472-3111, or visit Huskers.com.