This wizard step is only available if you've applied data grouping in the previous step (Step 5 - Add Grouping Levels). If you haven't grouped data, this step is skipped.
This page displays all available numerical and date-time fields that aren't used to group data. Using the check box table, you can specify which functions should be calculated for these fields.
Sometimes, data fields can contain empty values (this is different from, say, zero in a numeric field). If you don't want to take these values into account when calculating totals, check Ignore NULL values. Otherwise, these values will be treated as zeros for numeric fields and the earliest system date for date-time fields.
You can stop the wizard on this step by clicking Finish. In this case, your report will look similar to the image below.
If you want to customize your report further, click Next to proceed to Step 7 - Choose Report Layout.