Vertica client 5.1.6 - unixODBC error - Database does not exist

Hello,
I recently upgraded 4.1 client & driver to 5.1.6. I am setting up a connection to 6.1.3 server. Connection with vsql client works. However, connecting with isql fails. Appreciate ideas from folks here in resolving this. Below is the error message and also my ODBC setup. 

Error with isql:

$ isql -v Vertica6DSN my_user seekrit
[3D000][unixODBC][Vertica][VerticaDSII] (160) Connection attempt failed: FATAL:  Database "public" does not exist
[ISQL]ERROR: Could not SQLConnect

vsql works:

$ vsql -h vertica-01.dev.net -U my_user -w seekrit
Welcome to vsql, the Vertica Analytic Database v5.1.6-0 interactive terminal.
Type:  \h for help with SQL commands
       \? for help with vsql commands
       \g or terminate with semicolon to execute query
       \q to quit
my_user => \d;
                 List of tables
 Schema |   Name    | Kind  |  Owner  | Comment 
--------+-----------+-------+---------+---------
 public | regevents | table | dbadmin | 
(1 row)

ODBC DSN is:

$ cat /etc/odbc.ini

[ODBC Data Sources]

[Vertica6DSN]
Driver     = /opt/vertica/lib64/libverticaodbc.so
Host       = localhost
ServerName = vertica-01.dev.net
Database   = public
Port       = 5433
TxnReadCommitted = 1

Vertica.ini file:

$ cat /etc/vertica.ini 
[Driver]
DriverManagerEncoding=UTF-16
ODBCInstLib=/usr/lib64/libodbcinst.so
ErrorMessagesPath=/opt/vertica/lib64
LogLevel=4
LogPath=/tmp