Aggregate evaluation time (page break) Jasperreports

[toz]

Hi all, 

we try to generate invoices through jasperreports library. All is fine  but we have an issue with calculating page sums on multipage invoices.

e.g. : 

Invoice with 10 invoice positions

Page 1 : contains Position 1-5 (position 6 doesn't match in space left --> will be wrapped to page 2) --> Pagesum should be sum of pos 1-5

Page 2 : should containt Position 6-10 --> pagesum should be sum of pos 6-10

Current situation is :

Page 1 ends with a dynamic (empty) area which is the beginning of pos 6 --> therefore page1 pagesum is sum of pos 1 - 6 which is wrong

My questions:

1. How to prevent pos 6 to start on page 1? If there is not enough space left, the whole pos 6 should be start at new page

2. Could I insert a pagebreak depending on the "current y-coordinate"?

3. Is it possible to calculate a certain aggregate function at the end of details section?

Thanks in advance

Tom