Grammy Award winner Lauryn Hill will not perform Saturday night during the African American Heritage Festival at Oriole Park at Camden Yards. The rapper-singer-songwriter pulled out Tuesday. No reason has been given. Hill's replacement is R&B singer Vivian Green, who performs on the main stage at 7:30 Saturday evening, followed by Mint Condition at 8:30. The soul band, whose latest CD is Livin' the Luxury Brown, was originally scheduled to play Sunday afternoon at 4:30. Instead, Friends of Rudy Faulkner will perform at that time, followed by Faith Evans at 5:45.