We have been told that this is no longer supported by UPS as they have removed it from their integration.
Please call your UPS representative and ask for Part #01774501. These are the self stick labels that work with Store Manager. Rip off the label and slap it on the box. UPS should provide these labels to you at no cost. If that doesn't work you can always print off your labels on plain paper, fold the paper in half and stick it a UPS-supplied pouch. These pouches are free as well (sorry don't have a part number).