Hi and welcome to the forum.
Kernel 2.6.31-17 is available only on proposed repository, and I do not provide packages for proposed updates.
Anyway, you can easily build your own package starting from the packages sources.
There is no branch for 'nc10-backlight' on my launchpad account; instead, you can get the sources (.tar.gz) of the latest available version directly from the repository page (link
The version of the built packages is detected automatically during the build process by parsing the changelog, so all you have to do is to edit the file 'debian/changelog' and change the version to the one you want to build for.
In other words, change the line:
nc10-backlight (2.6.31-16~ppa1~nc10~karmic) karmic; urgency=low
nc10-backlight (2.6.31-17~ppa1~nc10~karmic) karmic; urgency=low
then use 'dpkg-buildpackage' to build the new .deb packages.
Obviously, make sure the needed dependencies for building the packages are installed (in this case, you need 'linux-headers-2.6.31-17-generic' installed).
Please consider a little donation to keep the 'Linux On My Samsung' project up and running. Thank you!