How to get hours of future absence entries in Global Absence Discretionary Disbursement Rule?

We have a scenario where when an employee is applying for Disbursement for a vacation type, the hours from any future absences should be deducted. For e.g. Max for absence plan is 32 hours, If employee has applied for 16 hours of absence in future, they should not be allowed to apply for more than 16 hours in disburements. I have attached the formula text I have used, but it is not restricting the employee from using all 32 hours in disbursements.

Has anyone created similar restrictions?