Mostly there are multiple perl, DBI, ... on your box.
Check which perl is used; what is its version; what library paths are under this Perl; where is your DBI, where is the DBD::Oracle under the DBI. And then you need set the environment before call the script; or have the environment set in the BEGIN block (some time you may need to call back the script in the BEGIN block that set up the environment before use DBI).
