Our frames pages have 3 selections that must be made. Be sure that all option selections have a blue circle. Otherwise, it isn't selected and will likely not let you complete checkout.
First, the frame. Even if there is only one color, be sure there is a blue circle around it.
Second, the lenses. You must choose indoor, outdoor, or transition lenses.
Third, the Prescription. Select "Yes" if you need to enter a Single Vision, Progressive, or Reader prescription. Select "No" if you need ready-made, non-prescription lenses.