[EDIT] i'm using canon pixma mx320 [\EDIT]

i have dual boot system of archlinux and gentoo.
when i scan documents in archlinux (using simple scan) it scan all the documents from the feeder.
but when i'm on gentoo (and again using simple scan) it scan only the first page in the feeder.
the second page is inserted a little bit into the scanner and then stopped, and it doesn't scan it and just stay idle and nothing is working from that point onward.
i need to press a printer button to cancel the "scanning" and after that the page is getting out from the other side (without scanning it of course).
if you could help me solve this issue it will be great :-).

It could be a Page Size problem. See this related topic from Canon for a possible hint.

thanks but if it was page size problem i think the problem was also on archlinux but there i can scan all the documents without a problem.
also, in gentoo it scan the first paper always.
the problem is from the second one.
and of course all the papers i scan are in the same size.

UPDATE!!!!
i downloaded VueScan in gentoo and now i can scan multiple documents from the feeder (with watermark).
so i think the problem is not with gentoo or the settings (of SANE for example).
in archlinux i have newer version of simple scan, so i'll wait for an update in gentoo simple scan package (that i think will solve this issue).

and thanks again :-)