Hi Sarah,
Try this:
valueexpression=CONCAT(ROUND(DATEDIFF({actualStartDate},$$TODAY),2)," Days")
valuefield=actualStartDate
linkedname=direct
valueformat=HTML
aggregator.valueexpression=CONCAT(ROUND(DATEDIFF({actualStartDate},$$TODAY),2)," Days")
aggregator.function=SUM
aggregator.valueformat=HTML
aggregator.displayformat=HTML
displayname=
namekey=$$TODAY
textmode=true
The result will depend on the time in the actual start date field compared to the time of day when you run the report.
Hope this helps,
Teale