Attempt to connect to database using libpq++ PgDatabase class fails because CONNECTION_BAD

I am porting code from Red Hat Linux to Windows 2000 and can not connect to a
my database using libpq++.

I have installed CygIPC and PostgreSQL as Services on my Windows 2000 PC.
I have created a database (called mediadb).
I have added tables to the database.
I have added data to the tables.

I can access the database using psql from a Cygwin Bash Shell (e.g.):

$psql -q -d mediadb -U mediadbuser

mediadb=# select count(*) from guide_programinfo;
count
-------
24532
(1 row)

I can not access the database from my application using libpq++ (CONNECTION_BAD):

#include <stdio.h>
#include <iostream>
#include <string>
#include "libpq++\pgdatabase.h"

using namespace std;

int main(int argc, char* argv[])
{
PgDatabase myDB("dbname=mediadb user=mediadbuser");

if ( myDB.ConnectionBad() )
{
>>> cout << "Failed to open <dbname=mediadb user=mediadbuser>" << endl;
}
else
{
cout << "Opened <dbname=mediadb user=mediadbuser>" << endl;
}

return 0;
}

I am using standard (unmodified) configuration files:

C:\cygwin\usr\share\postgresql\data\pg_hba.conf
C:\cygwin\usr\share\postgresql\data\postgresql.conf
...

Any help would be greatly appreciated!