File system level backup from 32bit to 64bit

i wanted to move my database from a 32bit machine to 64bit machine with rsync
like it is explained here

http://www.postgresql.org/docs/8.1/interactive/backup-file.html

I did an inital rsync while database was running. then shutdown, rsync again,
starting 64bit database says:

/var/lib/postgresql/8.1# /etc/init.d/postgresql-8.1 start
Starting PostgreSQL 8.1 database server: main* Error: The server must be
started under the locale : which does not exist any more.
 failed!

The locales are exactly the same when i list them with

   locale -a

i guess that rsyncing all database files from 32bit to 64bit does not work.

if so:
1. the error message is misleading.
2. It is not obvious for me that you can't copy from 32bit to 64bit. Maybe it
should be mentioned in the docs.

kind regards,
janning