Install fails on Debian sid

Cannot get Postgres 8.2 working on Debian sid using the Debian package.
At the config stage I get a message telling me to run:-
pg_createcluster 8.2 main --start

Doing this (as root) produces the following output:-

Creating new cluster (configuration: /etc/postgresql/8.2/main, \
data: /var/lib/postgresql/8.2/main)...
sh: /dev/null: Permission denied
fgets failure: Success
The program "postgres" is needed by initdb but was not found in the
same directory as "/usr/lib/postgresql/8.2/bin/initdb".
Check your installation.
Error: initdb failed

But the program postgres IS in the same directory as initdb

8.1 installed OK on my Etch server so I tried that on sid
Same result

Anyone any ideas?
--
Regards, Joe