Correct and Invoice on the AR List

Hi! I'd like to ask a question regarding invoices and accounts receivable, please. An invoice shows as Paid In Full in the AR List, but when I click on the invoice, it shows unpaid charges. I want to enter a payment, but when I enter the invoice number under "enter a payment", the invoice doesn't come up. It doesn't show any information so I can't enter a payment. Any ideas how I can enter the payment, please? Thank you!!