In order to complete a refund, Stripe needs to be able to transfer funds from your Stripe account to the ClassroomParent platform account, so it can return the funds to the credit card issuing bank.
If there are no funds in your Stripe account, or the amount in your Stripe account is less than the amount your are attempting refund, the refund will fail.
There are a couple steps you can take to ensure you have sufficient funds to complete the refund. You will do both of these through your Stripe account.
Once you have sufficient funds, you can reattempt to refund the transaction.
If you continue to have challenges refunding transaction, please reach out to ClassroomParent support and we can help.