When Validating an Invoice in AP,how can we alert the user about unbalanced entries realtime?

Company(Segment1 which is our balancing segment) may not be entered with correct values sometimes.Sometimes the user types in the wrong segment1 on invoice distribution.When validate accounting runs,if the supplier setup is wrong then this generate unbalanced entries.How can we make the system catch these unbalanced entries and stop them from being created ?

Thanks in advance.