This very humble monk would suggest you start by verifying that you have the DBI and DBD you need loaded properly. Something like

#!/usr/bin/perl
use DBI;

  print qq{Available drivers: }.
    join(", ",&DBI::available_drivers()).
      qq{\n};
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should return something like this: note Oracle appears alive and well in the list.

Available drivers: DBM, ExampleP, File, Gofer, Oracle, Proxy, Sponge
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But what do I know, I'm not even an initiate yet. However I'm learning, thanks to the Monastery.