Approve eCheck Refund Transaction - Transaction Not Found

[minhtuanta]

When I do a refund for an eCheck transaction in sandbox, the refund transaction is pending for approval. Rejection is fine. However, when I try to approve, I keep getting error "Transaction not found". Is there anything I need to do to make it work in sandbox?

[Short69]

Refunds on credit card purchases usually take 7 days. Credit card refund times vary by merchant and My CC Pay, with some taking a few days and others taking a few months.