Subtotal in pagefooter deriving from a subreport

Hi everybody

using a report for invoicing. Detail section contains a subreport in which i
accumulate certain field (price, qty, result of qty * price) overGroup and in
another textbox overAll, e. g. "AmountSum"

for subtotalling per page i use in the pagefooter another textbox with
"=SubReport!AmountSum" as controlsource.

the problem i have is, that in the pagefooter is not shown the true total of
the page (which shows up properly in the Detail Section - if i display it)
but the true total of the page PLUS the value of the first line of the
following page. (Example: accumulated value in "AmountSum" may be 500, the
first line on next page is 50. the pagefooter shows 550 instead of the
expected 500).

Why? Can anybody help me.

Thanks

Ulrich