If your jelly failed to solidify, you might not have dissolved the kanten powder completely or cooked it long enough. Stir it constantly and boil or simmer it for 2–3 minutes. If you substituted powdered gelatin or agar-agar, the brand you used may require more or less to solidify than the amount I suggested. Test (substituting 8 g or 4 tsp powdered gelatin or agar powder for 4 g or 2 tsp kanten powder) to make sure the jelly sets. Follow the package instructions for how to dissolve the gelatin. Also, remember that gelatin won't solidify if it's heated for too long or boiled.