Invoice and payment are entered using the wrong GL period.

This error can be serious due to the fact that it can affect the GL postings for prior periods.  If the invoice and payment were both posted to a prior period, the check and invoice must both be reversed in the prior period.  If only the check is voided, the invoice will be reopened, (but the report printed at the end of the period will not be changed), and the AP sub-ledger will go out of balance (won’t match the GL).

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Wrong check number or cash account is used during payment processing.