Revaluation is meant to capture the change in OPEN currency transactions from the transaction date (date on the open payable or receivable as example), to the period end date (last day of the month). So to test it out, make sure you have true open vendor bills or customer invoices on a date earlier than the accounting period end date you are testing, then run revaluation as of the period end - say 2/28 or 3/31 as potentially closed accounting periods since the 2/12 and 2/14 dates you mention above.