In order to use Bank Reconcile to reconcile an Account, you need to find all transactions and check them off. There may be some transactions that require a Voucher be made if it is missing from the list of Un-Reconciled Transactions.
To create a voucher there is a simple Quick Voucher section below the list of Unreconciled Transactions.
If you discover a missing transaction simply fill out the Quick Voucher section just like a normal Voucher, then choose the Create Voucher/Check button
The system will instantly create the transaction and allow you to select it in order to complete the Bank Reconcile for the Account.