I'm wondering if you could simply have a calculated field that would assign a group? It would look something like:
IF Days_Since_Received <= 15 THEN "1 - 15"
ELSE IF Days_Since_Received <= 30 THEN "26 - 30"
But I'm not sure exactly what you want to do with 45+ or if there are other considerations with your data or exactly what you are trying to achieve.
Do you happen to have a packaged workbook you could post?
If you have a limited number of buckets, Joshua has the ideal answer. If there are more, or you wanted to be more finite than 15 days, you could also dynamically create the groups using a calculation. See the attached - it uses a parameter as the base date and a calc to work out the number of 15 day blocks:
str(int(datediff('day',[Base Date],([Order Date]))/15)*15)+" to "+str(int(datediff('day',[Base Date],([Order Date]))/15)*15+15)+" days"
The essence is int(datediff('day',[Base Date],([Order Date]))/15)*15 which is give me the number of days between the date and the base date, divide it by 15 and take the integer value (i.e. give me the number of 15 day blocks), multiply this by 15 to get the numbers 0,15,30 etc.
Dynamic groups.twbx.zip 417.1 KB