This occurs when the system believes the table is being held open by a clerk.

The first step is to press the table number button which will list any open tables.  It will list the tables and where the system believes the table is held open it will show the clerk number that has it open and the ECR that it is open on.  At this point, you should ask that clerk to logon on the till listed and open the table.

If this still fails the next step is to perform a reset of the balance busy status.  On your manager screen, you will find a button that says 'Reset Balance Busy Status'.  Log on to your master till and press this button.

This will allow you to open the tables and deal with them