Connecting to a 7.1 DB with 7.3 psql

I'm having trouble connecting to a 7.1 database with the 7.3.2 client.
It seems that my user privileges are severely restricted.
Check out this interaction:

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[demo@trout ~/database_dumps]# psql -Usts -h winnie sts
ERROR: parser: parse error at or near "."
Welcome to psql 7.3.2, 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

sts=> select version();
version
--------------------------------------------------------------
PostgreSQL 7.1.3 on i686-pc-cygwin, compiled by GCC 2.95.3-5
(1 row)

sts=> \l
ERROR: parser: parse error at or near "("
sts=>
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The version of psql is obviously 7.3.2. I compiled it myself from the SRPMs from postgresql.org on this RedHat 6.2 system (trout). The server is obviously running on cygwin, and I don't suspect that's the problem. What could be happening here? User sts owns the database named sts. Connecting with a 7.1 client works fine.

I'd appreciate any suggestions!

-Roland