Transportation Calendar Setups

I am trying to do the setups to limit the scheduled ship date on orders to always land on a Wednesday.  I created a calendar whose only active day was Wednesday.  Assigned that calendar to the carrier and defaulted that carrier on the customer site.  When creating the order it uses the ship method defined in the setups BUT the schedule ship date is not limited to the Wednesday.  We are running ASCP.    Can anyone give me guidance as to what may be wrong with my setup or logic?