What Causes Delayed Periods After Taking Emergency Contraceptive Pill And Primolut N?

Hi.. my intercouse was on 3rd january i took ecp tablet to avoide pragnency. I took primolut n 3 times a day for 5 days. Just to make sure that my periods vl b in time. But today on 20th january my periods due date i am not having periods. Is it the effect of tablets