How can I get these children motivated?

I live in a poor black township in South Africa. I am a community worker trying hard to get children off the street and to school. The children I work with are negleted,abused, their parents are alcoholics, hiv positive or have died from HIV and aids, some of the children are HIV positive. My question is how can I continue to motivate them to stay in school. I try my best to give them incentives like taking them on trips and outings around cape town, offer them emotional support, help them with school work, and offer them financial support. What more can I do in order to get them to understand that education is the only way for them out of poverty? Sumtimes I want to give up, I loose heart! HELP!