FILE - Former U.S. President Jimmy Carter, background second right, former U.N. head Kofi Annan, background right, and Graca Machel, the wife of former South African President Nelson Mandela, background second from left, watch children perform during a visit to the Central Methodist Church in Johannesburg, South Africa, Nov. 23, 2008. The diplomats were barred entry into Zimbabwe on a humanitarian visit over the weekend. (AP Photo/Denis Farrell, File)