start/stop error message

I am unable to solve the following problem.

When I start or stop PostgreSQL using pg_ctl (without the -D option) the
system works fine. No errors. I have the PGDATA environment variable
set and it points to my cluster.

When I run the /etc/init.d/postgresql-8.2 script with either of "stop"
or "start" as parameters I get the following error:

david(at)kepler:/etc/init.d$ sudo /etc/init.d/postgresql-8.2 start
* Starting PostgreSQL 8.2 database server
* Error: specified cluster does not exist
[fail]

and the same error when passing "stop"

The cluster clearly exists and is recognized by pg_ctl. As a result
PostgreSQL does not start with the system and must be started and
stopped manually.

I am running Ubuntu linux (very close to Debian).

There must be a configuration error but I cannot find it.

David