How to prevent then Gain/Loss generate in the secondary ledger which currency code is the same as t

Hi：

      Our ebs Applications is12.1.1. Our primary Ledger's Currency code is CNY, Secondary Ledger's currency code is USD . There is always  Credit memos  which are  USD ,and then Gain/Loss lines will be  generated in primary ledger, and also  will be  generated  in the secondary ledger.This will be a EC12 error when we run the concurrent report 'Submit Accounting '.

     The   Credit memo is USD ,and the Secondary Ledger's currency code is USD,  the Gain/Loss lines is unmeaningful.

     So ,is there any way to prevent this be happened?

     Thank you!