Apply Credit Memo (on a closed period) which is less than the Invoice Amount and No Payment is Received.

-- Open the Customer Record then click on Accept Payment button.
-- On the New Payment page> Apply tab> Invoices sub tab> mark the Invoice the Credit needs to be applied to and Payment column must contain Credit Amount.
-- Then go to Credits sub tab> mark the Credit Memo.
-- Take note of the *Payment Amount it should be (0.00) zero if the Credit Memo is less than the Invoice Amount.
-- Save.