The Bank Reconciliation process in Manager is a little different to how other programs might manage the process. So, just to find out what steps you may or may not have gone through, have you seen the guide here: Reconciling bank accounts
Do you have a Cash Account set up?
If so, did you tick the box This account is maintained by a bank or other financial institution when setting up the Cash Account?
Under Reports, Do you have a Cash Accounts section?
If so, do you have Bank Reconciliation Statement option?