CR9.0, cant set Details section's height : its disabled. the details section goes too far down and FORMAT SECTION - DETAILS- LAYOUT not changable

hi, i have a report in the normal format

HEADER

DETAILS e.g.
DETAIL 1
DETAIL 2
DETAIL 3
DETAIL 4

REPORT FOOTER
PAGE FOOTER
                                                   TOTAL 1
                                                   TOTAL 2
                                                   TOTAL 3

but when its printed , it comes out like this:
DETAIL1                                       DETAIL4
DETAIL2                                       DETAIL5
----------------------------------------------- (should stop here)
DETAIL3                                                (this one should go to top)
                                                  TOTAL 1
                                                  TOTAL 2
                                                  TOTAL 3

i want crystal reports to know not to go past a certain point in the details section, thus
dont make DETAIL3 at the current position, go to detail 4's position.
i tried to go to format section - details - layout, but for some reason i cant set the height of details section
please help! thanks!