[twitter-dev] Friendships.create returns successful but does not work

[NW]

I'm trying to setup a script to follow a specified user.  When I run
it it returns the user's information as described in the documentation
as a successful result.  However, when I go to look at the user
account, it's not following anyone.

This is the code I'm using in php:

$ch = curl_init( 'http://twitter.com/friendships/create/
usernameToFollow.xml');
        curl_setopt_array($ch, array(
                CURLOPT_HEADER => true,
                CURLOPT_RETURNTRANSFER => true,
                CURLOPT_CONNECTTIMEOUT => 10,
                CURLOPT_TIMEOUT => 10,
                CURLOPT_FORBID_REUSE => true,
                CURLOPT_FRESH_CONNECT => true,
                CURLOPT_FOLLOWLOCATION => 1,
                CURLOPT_SSL_VERIFYHOST => 0,
                CURLOPT_POSTFIELDS => 'follow=true',
                CURLOPT_USERPWD => 'xxxx:yyyy'
                )
        );
        $resp = curl_exec($ch);
        curl_close ($ch);

Any idea what's happening here?