psql to 7.2.3 from 7.3.1

Hi,

I have pg7.3.1 in my PC and pg7.2.3 in another machine. While i tried psql
pg7.2.3 from pg7.3.1 machine, it reports

ERROR:  parser: parse error at or near "."

But still, it established the connection. Then it was found that i was
unable to execute any of the forward slash (\) commands from that version
of psql. It reports similar error for every forward slash (\) commands.

Does it due to the fact that psql of 7.3.1 has more features than 7.2.3
does? How can i overcome this problem? Does using 7.2.3 or 7.3.1 on both
machines the only way?

Sample test:

$ psql -V
psql (PostgreSQL) 7.3.1
contains support for command-line editing
[bhuvan@Bhuvan bhuvan]$ psql -hdbserver test_db test_db
Password:
ERROR:  parser: parse error at or near "."
Welcome to psql 7.3.1, the PostgreSQL interactive terminal.

Type:  \copyright for distribution terms
       \h for help with SQL commands
       \? for help on internal slash commands
       \g or terminate with semicolon to execute query
       \q to quit

SSL connection (cipher: DES-CBC3-SHA, bits: 168)

test_db=> \dt
ERROR:  parser: parse error at or near "."
test_db=> SELECT version();
                           version
-------------------------------------------------------------
 PostgreSQL 7.2.3 on i686-pc-linux-gnu, compiled by GCC 2.96
(1 row)

test_db=>

regards,
bhuvaneswaran