Home Currency revaluations unrealised

Hello

I have a foreign currency loan which I want to revalue at year end. It is set up under the category of "other liabilities". When I run the multi-currency revaluation at end of year, it posts the fx gain/loss to realized, instead of unrealized. It should be unrealized, since it is still open and I want just a paper adjustment.

Question: How can I revalue a foreign currency liability and get the fx gain/loss posted to "unrealized gains and losses"? Do I need to make some change in the chart of accounts area? Thanks !