Actuals and Reporting currency ledger balances not matching

Hi

We have a strange problem in our company. We have a US and Canada LEs. So we have USD_Actuals and CAD_Actuals for these LEs. And have CA_USD_REP as reporting ledgers for Canadian business. Of late, the balances in these two ledgers, USD_Actuals and CA_USD_REP does not match. They are consistently off every month and there is no pattern there to cross check anything. We have Corporate rate for exchange rate from CAD to USD for CA_USD_REP ledger.

Can someone please help me how to check for any errors in setup or what else to do. I am completely lost on what I should be doing.