Run dpkg -c on your package and check what the permissions/UID/GID on the files you're installing are. If you were using dpkg -b, it's easy to mess up and install files with incorrect permissions.

However, what I'm recommending is to build a source package directory structure and use dpkg-buildpackage from inside Scratchbox, rather than using either Qt Creator or dpkg -b. The build process normally ensures permissions are set correctly, and once you're familiar with Debian source packages it can be really easy to port certain programs/utilities to the N9. It also automatically takes care of everything for Aegis, which has to be done manually if you use dpkg -b instead.