The PMS has the ability to report on potential revenue that was lost from the cancellation of a group.
Operations > Groups > Reports > Cancelled Groups
This report will ask for a date range to be selected and the date range is based on the Group Dates, not based on the cancellation date.
NOTE: The results will display the total amounts for the group. For example, if the group was arriving on September 30 for three nights, and the report was run from Oct 1 to Oct 31, this group would still display with total Room Nights and Revenue, including the data from September 30th.