What Causes A Longer Menstruation Period Since Using Daphne?

hi.im using daphne pill for the first time.im using it now for 2weeks now.my last menstrual period was last may30 and i started using the pill on the 2nd day of my menstruation.my usual duration of menses was 4 days.Why is it that until now my menstruation still occurs,it didnt stop since i started using the pill