Multiple grouping / sorting problem

I've got trouble with a report I'm building up that isn't sorting properly.
It's an invoice report, which displays all invoices for a given day, however, the order lines aren't grouped by invoice, they are by article type and article. Crystal however still sorts by invoice number and then applies my grouping.
This results in multiple entries for a given type if there are more than one invoice with the same type on a given day. How can I convince CR to not sort by invoice. Oh, no I'm not using a querry, I've got a dataset with all relevant information linked to CR with an XML Schema.

Here is a breakdown of it:

InvoiceDate
- Element Type
- Invoice Element
-Invoice Element Sub categories.

And this is how it displays:

7-9-2006
Accomodation
Hotel
2PK Room
Flight
Return Ticked Paris
Business Class
[ and now comes the 2nd invoice on that day ]
Accomodation
Motel
Bride Suit
Flight
Return Ticket London
Economy class

What it SHOULD be:

7-9-2006
Accomodation
Hotel
2PK Room
Motel
Bride Suit
Flight
Return Ticked Paris
Business Class
Return Ticket London
Economy class

Anybody got any ideas?
I'm using Visual basic .Net 2003 and the crystal reports editor that came with that.Right... something I forgot to mention.
This report can also be used to sort on depareture date.. which the original builder had added as a group along with invoice date, and displayed the one that he needed.. ofcourse crystal still GROUPS by this group even if it's not visible. hence my sort order got messed up.