libpq, Large Objects, Type lo

I have an app written in Borland C++ Builder accessing Blobs in the database

All is well, I have set up the user defined type of "lo" and
the Borland Windows app add/deletes blobs beautifully.

The problem comes in the unix enviroment, where I would like to interact
with the blobs via libpq.

How to I access these blobs...
-------------------------------

select image_oid from footable where image_oid is not null;

image_oid
---------
136001

but ....

select lo_export(image_oid),'/tmp/foo.jpg') from footable where image_oid is not null;

ERROR: No such function 'lo_export' with the specified attributes

this is from psql, and I get simialer errors from my small c proggie.

Thanks,
Travis