Graspop have basically said it's nonsense that Sabbath are playing there.
Quote: "Studio Brussel has news for you: apparently Black Sabbath is coming to Graspop Metal Meeting next summer.How nice of them to let us know! Perhaps Studio Brussel can reveal a few other names even we don’t know about? No, seriously, Graspop Metal Meeting is the only channel for official GMM communications"
18/12 Black Sabbath
14/1 Iced Earth
18/1 Lamb of God