Grouping numbers in a pivot table?

Hi All

I'm trying to group a numeric field in a pivot table so that something like:

Credits earned
10 11 13 15 20 21 25

becomes

Credits earned
10-15 16-20 21-25

But when I select the numeric values in the credits earned field and try to group them it just creates a new group called "Group 1". I've run into this problem before intermittently and sometimes I can get the grouping to work and sometimes not. I've made sure there are no blanks or text values in the field values, so I'm at a loss here... help is appreciated!

I'm using Excel 2003 on Windows XP if that helps.

Thanks!

Orville

First I had to ungroup the previous groups by selecting them and choosing Data> group and outline> ungroup. Then instead of selecting the values in the field, I selected just the field name and then chose Data>group and outline. This gave me the "Starting at" "Ending at" and "By" options for grouping the numbers into ranges. Looks like I solved it. We'll see if this works next time.