The key here is dbi:Oracle:db2 - you're using Oracle. The Oracle libraries need to have several environment variables set before they will load at all.

As I already mentioned in the chatterbox, several times, you want to load the environment variables, best before launching your Perl script. Either do this by writing a small shell script wrapper around your Perl script that sets up the Oracle environment or set up the environment manually by setting the values in %ENV from within Perl, or use, as I pointed out, Get Default Environment or a variation thereof to load the environment values set up by some shell script. A module similar to that node is Shell::EnvImporter.