Hi Mandy_L
Out of curiosity, if you go to: Banking > Bank Reconciliation and enter the relevant account and date, do you have any unreconciled transactions showing here?
If you do, these will still add to the Account Balance but won't be calculated if left unchecked which could mean that the Reconciled balance is incorrect as you would need to check ALL transactions to make sure the Calculated Balance is married up to your actual Reconciliation Balance.
I would also recommend checking the Calculated Statement Balance, here's a good support note showing how to check this: Resolving out of balance bank reconciliations
Keep me posted on what you find.