scan in black and white doesn't work

Binary package hint: simple-scan

My ubuntu release : Kubuntu 10.10
Simple-scan version : 2.32.0

To begin with, sorry for my english

I can't fix a problem with simple-scan : when i scan in black and white (ie as a text), the file that is created by simple-scan is a PDF document. But when i launch okular to read it, the error message is : impossible to open this file.

Then i've scaned the same document in color (ie as a photo in simple-scan) and for this case, there is no problem.

 So, what's the problem ?

ProblemType: Bug
DistroRelease: Ubuntu 10.10
Package: simple-scan 2.32.0-0ubuntu3
ProcVersionSignature: Ubuntu 2.6.35-22.35-generic-pae 2.6.35.4
Uname: Linux 2.6.35-22-generic-pae i686
Architecture: i386
Date: Tue Oct 26 20:43:04 2010
DriverPackageVersions:
 libsane 1.0.21-2ubuntu2
 libsane-extras N/A
 hplip 3.10.6-1ubuntu10
 hpoj N/A
InstallationMedia: Kubuntu 10.10 "Maverick Meerkat" - Release i386 (20101007)
MachineType: To Be Filled By O.E.M. To Be Filled By O.E.M.
ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.35-22-generic-pae root=UUID=019f4dcd-efbe-4712-8d70-1320ccc7588e ro quiet splash
ProcEnviron:
 LANG=fr_FR.UTF-8
 SHELL=/bin/bash
SimpleScanLog:

SourcePackage: simple-scan
dmi.bios.date: 09/07/2004
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 1003.004
dmi.board.name: P4P800-E
dmi.board.vendor: ASUSTeK Computer Inc.
dmi.board.version: Rev 1.xx
dmi.chassis.asset.tag: Asset-1234567890
dmi.chassis.type: 3
dmi.chassis.vendor: Chassis Manufacture
dmi.chassis.version: Chassis Version
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr1003.004:bd09/07/2004:svnToBeFilledByO.E.M.:pnToBeFilledByO.E.M.:pvrToBeFilledByO.E.M.:rvnASUSTeKComputerInc.:rnP4P800-E:rvrRev1.xx:cvnChassisManufacture:ct3:cvrChassisVersion:
dmi.product.name: To Be Filled By O.E.M.
dmi.product.version: To Be Filled By O.E.M.
dmi.sys.vendor: To Be Filled By O.E.M.