A New York musician tweeted Thursday he will no longer perform at the SXSW Music Festival over a contract provision stating that U.S. immigration agents may be contacted if an international artist violates the performance agreement. SXSW organizers responded by saying that Felix Walworth, who goes by the stage name Told Slant, had misunderstood their policies and that no artist in the festival’s 30-plus-year history had been reported to federal immigration agents.