postgresql-8.4 error - Mailing list pgsql-general

i removed the postgresql packages using apt-get purge postgresql-8.4 and deleted all directories

and installed using apt-get install postgresql-8.4

and get this error

 * Starting PostgreSQL 8.4 database server                                                                          

                       * Error: /var/lib/postgresql/8.4/main is not accessible or does not exist