You have perl 5.6 installed. DBD::Oracle is installed in a 5.005 path. If you run your script with 5.005 (which is probably something like /usr/local/bin/perl5.005_03) it should work.

Or get a sysadmin to install DBD::Oracle for 5.6.

(I would recommend the former. 5.6.0 has a few bugs that I don't like. 5.6.1 is nearly out.)