What Causes Delayed Abortion Despite Taking Mifepristone And Misoprostol?

Hi, I had taken Mifepristone tablet, after 24 hours I had taken two Misopristol talblets orally with 6 hours gap. On the same day in the night I had taken remain two misoprostol vaginally after 6 hours of second dose. But still am not getting any bleeding. Please help us in this.