My client who uses to accept credit card payments is getting an error when attempting to do a partial refund for a sale via the ZenCart admin for the order. The error message that comes back when I try it myself is:

The referenced transaction does not meet the criteria for issuing a credit.

Am I correct that this message is due to the payment not yet having been captured in I know I have successfully done partial refunds for this client's orders in the past.

Any info would be helpful. Thanks!