Recalculate Commission: Percentage vs. Amount
For reservations that are marked as Non-Commissionable, the Commissionable Revenue will always start as 0.00. Therefore, if you attempt to apply the percentage (%) option for RECALCULATE COMM., the commission will post as 0.00. This is because no Commissionable Revenue is being recorded for the reservation, and accordingly a percentage of 0.00 will always be 0.00.
If you want to post a commission on a Non-Commissionable reservation, use the amount ($) option to add a value to the reservation, and the commission posted will be the desired amount.