Hi accounts158,
Before reconciling an account you will need to reconcile the opening balance posting (deposit or journal entry). To do this, got to Accounting > Chart of Accounts > Edit against the bank account and then select the 'Date' to reorder the transactions from earliest - oldest. Locate the opening balance posted here and mark this as reconciled by clicking into the transaction to expand and left-clicking the check column until this changes to 'R' then save.
When you then go to reconcile the account this will show as the opening balance.
Thanks