A journal change is made for the opening balance at the turn of a year. It can then happen that a zero entry occurs on the general suspense account (2999).
Both debit and credit then have a zero amount. Due to this zero line, the journal entry cannot be made definitive (with the result that an empty opening balance sheet).
The rule can only be deleted "manually" by the Reflecta help desk.
general ledger 2999 is usually used for the general suspense account, but this may be different for you, for this, see the Financial data company program.