Why is There a Negative Balance on an Order?
Issue: The below message is displayed trying to close an Order

Potential Causes: Confirm whether one of the below scenarios occurred
A Comp/OTH/Void was applied after payment was received.
A Promotion was applied to a Seat or Order after payment was received.
A Combo Item was "optimized" after payment was received.
Additional Item(s) were ordered on the table before the Order was closed.
If none of the above have occurred, please contact Flyght Support.
Related article:
How to Close an Unbalanced or Negative Order