Moved your question to this thread since it seems a bit more appropriate.
Anyway, to do that combo you'll want to do a couple of things. First, make sure you hit the 6A with your opponent as low to the ground as possible; the lower your opponent, the easier it'll be to get the j.2C part down. Second, make sure you're doing j.2C as soon as you can after the Cresent Saber cancel. Since that's where you said your problem is, could you elaborate a little on what goes wrong when you attempt that part so we can give you more specific help on that? Also, you might want to practice on a larger hitbox like Tager's since it's a lot easier to do that combo on him.