PHILADELPHIA - A woman was walking in Chinatown Monday morning when police say a teen tried to rob her from behind.The attempted robbery happened on the 1000 block of Vine Street around 11 a.m.Police say a teen suspect tried to pull a necklace and headphones from the neck of a 31-year-old woman.He was unsuccessful, but left the woman with scratches to her neck, according to authorities.MORE HEADLINES:The suspect fled the scene, and was last seen on 10th Street.