Thanks DBlank for the prompt reply but I'm not sure I understand. I'm very new at this.
I want to compare a range that the user inputs against the same period last year.
User inputs two dates Date_1 and Date_2
For each of Date_1 and Date_2, I have used the following to define my last year's dates as Date_start_LY and Date_end_LY and get the correct results:
DateAdd( 'Y', -365, {?Date_2})
However, when I try to use the two dates to select records it fails. Have I not used the date fields correctly in the following selection?
IF {SALES_ORDER_HEADERS.SYS_SHIPPING_DATE} in {Date_start_LY} to {Date_end_LY}