Misinterpereting instance as part of server

I have a FreeTDS/odbc source that appears to be trying to resolve the server and instance of "servername.domain\db1" as a server instead of a server called "servername.domain"
and an instance "db1"



I know this should work because I have two linux servers using the same exact odbc source.
Server A works.
Server B doesn't.

SERVER A:
-------------------------------------------------------
A Redhat server.
Using a data source in odbc.ini, I can connect to a particular MS SQL server and instance with the following server name in the source definition:

Server = Servername.domain\db1

Some info from that server:

$ tsql -C
Compile-time settings (established with the "configure" script):
                           Version: freetds v0.64
    MS db-lib source compatibility: yes
       Sybase binary compatibility: unknown
                     Thread safety: yes
                     iconv library: yes
                       TDS version: 4.2
                             iODBC: no
                          unixodbc: yes

$ odbcinst --version
unixODBC 2.2.11


SERVER B:
-------------------------------------------------------
Debian Etch (old) server:
FreeTDS and odbcinst work perfectly Server B when accessing any of several MS SQL servers.
I am able to connect to several MS SQL servers from this machine, but only if they don't require an instance.

Using the exact same data source definition as Server A, I am unable to connect to the same MS SQL server of "servername.domain\db1"

The error message is:
failed: [unixODBC][FreeTDS][SQL Server]Unable to connect to data source (SQL-08001)(DBD: db_login/SQLConnect err=-1)

Also, tcpdump shows that the command never leaves server B. It appears that it is trying to resolve the server "servername.domain\db1" instead of "servername.domain"

When I remove the instance from the server, I get a "connection refused" error - which means I am at least reaching the MS SQL box but it doesn't do me any good because I need the instance to connect.

It appears that the server instance (\db1) is getting interpereted as part of the server name.

Some info from server B.

# tsql -C
Compile-time settings (established with the "configure" script)
                            Version: freetds v0.83.dev.20090814
             freetds.conf directory: /usr/local/etc
     MS db-lib source compatibility: no
        Sybase binary compatibility: no
                      Thread safety: yes
                      iconv library: yes
                        TDS version: 5.0
                              iODBC: no
                           unixodbc: no


# odbcinst --version
unixODBC 2.2.11