Receipt Amount is not equal to Remittance Account

Hi,

I have an issue wherein the Receipt Amount is not equal to Remittance amount.

For example:

Receipt Amount =          1,000.00

Remittance Amount =       980.00

Cashier Shortage =             20.00

How can we handle this? I found that the Receipt Amount in the  Remittance form  cannot be updated and partial remittance is not allowed?

Please advise.

Thank you very much for the help.