data_sources was updated in more recent versions of DBI.

You are using DBI 1.13, which is four years old.

Get an upgrade (DBI).
update Since you seem to be using perl 5.00405, the latest DBI won't install. You may be able to install version 1.20, which still supports that ancient version of Perl. Time to think seriously about upgrading Perl as well!

Your snippet runs just fine on my machine (with DBI 1.33 and DBI 1.38).