Perl dbi interface v0.73

I'm using the DBD-Pg-0.73 package from Edmund Mergl. The environment is
Postgresql 6.3.2 (0.73 says it is for this version), RH linux 5.1,
mod_perl 1.18 with apache 1.3.4. I've had a great time with the DBI
portion of the interface. However, when I try to access the large object
interface from within perl my code exits without an error. The line in
question is:

$ofd = $dbHandle->Pg::lo_open($imgOID, 'PGRES_INV_READ');

$dbHandle was created sucessfully since I execute an insert right before
this line.

Why can't I get the fd?

TIA