Date Overun Alert

Hi I have several control sheets that relay on ISBLANK to change the colour of a cell as a warning-like a traffic light. It is used to track maintenance issues against a fleet of vehicles and works well. Is it possible to use same conditional format "traffic light" to alert me if the period of days between todays date and an event date is over 14 days. I would like to track tachograph downloads from trucks and drivers and need an alert working from last download date recorded. Any help appreciated. Rgds nigel

Hi have sorted problem once I discovered how excel treats date inputs. Just asked system to alert if days between the two dates exceeds 14 and conditional formatted the cells to give me the traffic light