What Causes Delayed Vaginal Bleeding Despite Taking Cytolog Pills?

My wife took mefigest and 48 hrs took 2 cytolog orally. But her bleeding was very low then after 24 hrs she took 2 more cytolog orally but bleedinv was not at par then after 12 hrs at 6 pm on 29 march took 2 cytolog veginally but bleeding is not par. Pl advise. Thanks.