If you've used the Start a New Fiscal Year feature and then try to undo a reconciliation

When you Start a New Year in MYOB AccountEdge, you have the option of purging (deleting) transactions from your company file. If you try to undo a reconciliation in which some of the transactions have been deleted, you will receive an alert message.

We strongly recommend that you don't undo a reconciliation in which some of the transactions have been deleted. If transactions that were necessary to reconcile the account the first time were deleted from the file during the Start a New Fiscal Year process and if you undo the reconciliation, you won't be able to reconcile the account again.