Medical exemption not in RT (India Payroll)

Hi

We are paying medical allowance as Tax Exempted every month.

Issue is for the leaver:

Employee left in July and his payroll for July is processed in August.

Now the issue is if i run simulation for July then it displays the medical exemption amount 

But when i run in the month of august retro to july then its not displaying the medical Tax exempted amount in payslip and in RT also.

What could be the reason.  I can see those amounts reflecting July RT but as payroll is run for august and in August RT this doesnot exist.

Please guide.

Thanks
Seema