Undefined symbol in plpgsql.so library

Hello Folks,

Don't know whether this is the right group to post the question, but at
installing an application that uses Postgres, I get the following message:

ERROR: Load of file /usr/lib/pgsql/plpgsql.so failed:
/usr/lib/pgsql/plpgsql.so: undefined symbol: xlateSqlType

The calling command is:

CREATE FUNCTION plpgsql_call_handler () RETURNS OPAQUE AS
'/usr/lib/pgsql/plpgsql.so' LANGUAGE 'C';

This is called from an OpenNMS installation procedure.

The library itself exists.

A scan with nm over the *.so libraries shows that there is NO symbol
xlateSqlType defined in any library on the system.

Postgres 7.3.4 is installed on Mandrake Linux 9.2.

Thanks, LM.