This error message may appear in Altru when you're attempting to add a flat rate scale with a group type that is already used on another flat rate scale. When creating flat rate scales in Altru you must use a unique group type that is not used on any other flat rate scales, or leave the group type field blank

You can check the group types used on your flat rates by following these steps:
  1. Click Tickets > Group Sales Setup
  2. Click Flat rate pricing
  3. The group type column will display all group types in use by other flat rate scales
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