Opening Balances are essential to having a correct conversion calculation. It's also important that the Opening Balances are loaded in the correct DataView and Audit members. 

Local currency data should always be loaded in the Value DataView. ‌The converted data should always be loaded in the Conversion member. 

Once the Opening Balances have been properly loaded in P12 of the previous year, it's essential to run the Copy Opening Process to ensure that the current year has the correct opening balances in the Opening Movement member. The Validation > Opening Period report is very useful for verifying that the opening balances are accurate in both local and reporting currencies.