BUG #17730: Trigger Issue

The following bug has been logged on the website:

Bug reference:      17730
Logged by:          n d
Email address:      nigel@oscsales.com
PostgreSQL version: Unsupported/Unknown
Operating system:   Windows
Description:

I have cloned a trigger from another table by inserting new rows into the
pg_catalog.pg_triggers but the trigger is not working and the following
querry -
select pg_get_triggerdef(t.oid)
from pg_catalog.pg_trigger t
returns the error 
cache lookup failed for attribute 7 of relation 1682781.
Is there something else I need to change ?