Withheld Amount get Reduced wrongly After applying Concession on Project Invoice in Project Billing

Hi all,

I tried to apply concession on Project Invoices (project standard invoice let say invoice#1 ) and it is working fine BUT I want to know how system is calculating the amount for reducing the Withheld Amount of previous project Invoice (i.e., invoice#1 )

Example that I have performed on system is below:

Let say, Event Amount= [ 53550 USD ] and Retention % = [ 10% ]

First Transaction (i.e., Invoice # 1 of above Event ):
Dr/ Receivable [ 48195 USD]
Dr/ Retenion [ 5355 USD]
Cr/ UnEarned Revenue [ 53550 USD ]

Now, At this stage Withheld Amount= [ 5355 USD ] at Retention Inquiry Screen 

Second Transaction ( i.e., Apply Concession AMount = 100):
Dr/ UnEarned Revenue [ 111.11 USD