Group field in Body Section

I have some records printed on a Body Section. How can I group my records by a field on a Body Section?

I have a Item category Code on my sales line invoice.

I must goup my records by item category code and make a Sum by each group.

How vcan I do It?

Note: I tried this procedure, using a footer section but with this option I get another problem.

You have do it with GroupTotalFields = Item category Code

Add the fields in GroupFooter (not in Footer)

If I implement your suggest, if the first line in sales invoice line = Type= Resource, the next records in sales invoice lines are not printed.

If the body section is call in first, the data in groupfooter is not printed.

Do you know why??

is the next line also has type = resource and Item Category Code as first line?

1ª line I have a type= resource

2ª line if type = item, does not print in report this 2ª line

if type = resource both lines are printed, 1ª and 2ª

In both types I have Item category code associated, but only on type = Item I group and make a total for each Item category code.