Well, as you may know we don't officially support Debian, but I can tell you that your method is missing some steps. Besides installing the rpms many of the components also have post install scripts that need to be run. You can try running:
find /usr/local/natinst/ -name "*InstallerUtility.sh"
Then for each result returned run:
. <product>InstallerUtility.sh
<product>PostInstall
You also may have better luck if you simply installed rpm on your system and then use the supplied INSTALL script, but you may run into different problems that way.
Shawn Bohrer
National Instruments