Sales Price Report, group by Item No & UoM

Hi,
I try to make a simple report. Only using 1 data item Sales Price. set tableview using the first key : Item No.,Sales Type,Sales Code,Starting Date,Currency Code,Variant Code,Unit of Measure Code,Minimum Quantity.

Set the GroupTotalFields : Item No.,Unit of Measure Code.
Create two GroupHeader, GroupHeader(1) & GroupHeader(2).

GroupHeader(1) to show item no. On PreSection put this code :
CurrReport.SHOWOUTPUT(CurrReport.TOTALSCAUSEDBY = FIELDNO("Item No."));

GroupHeader(2) to show Unit of Measure COde. On PreSection put this code :
CurrReport.SHOWOUTPUT(CurrReport.TOTALSCAUSEDBY = FIELDNO("Unit of Measure Code"));

Then on Sales Price Body, shows the Sales Code (Customer Code in my database)

I'm expecting the report will show like this:
ITEM1
======================
KG
CUST1
CUST2

PCS
CUST3

But instead, the report shows like this:
ITEM1
======================
KG
CUST1

KG
CUST2

PCS
CUST3

Any mistake on my code? thanks

Regards,
Alphonse