meaning of curl_multi errno 7 while using proxy

Question

I'm using curl_multi to test a set of proxies, which proved to be working before. My code is working fine, but I get a lot of errno 7 responses, which I find hard to understand:

Failed connect to example.com:1; Operation now in progress

Failed connect to example.com:1; Success

(example.com stands here for my actual server with test script)

in basic curl same addresses might return:

couldn't connect to host

What might be the actual meaning of those messages?

How I prepare each handle:

function prepare_handle($item) {
    $options = array();
    $options[CURLOPT_RETURNTRANSFER] = 1;
    $options[CURLOPT_REFERER] = TEST_REFERER;   
    $options[CURLOPT_PROXY]=trim($item['address']);
    $options[CURLOPT_FRESH_CONNECT]=TRUE;
    //$options[CURLOPT_CONNECTTIMEOUT] = CHECK_CONNECTTIMEOUT; // 20
    $options[CURLOPT_TIMEOUT] = CHECK_TIMEOUT; // 60
    $options[CURLOPT_NOBODY]=TRUE; // remove body       
    $url = HTTP_GATE . '?id=' . $item['id'];
    
    if($item['socks']>0) {
        // ustaw socks
        $options[CURLOPT_PROXYTYPE]='CURLPROXY_SOCKS5';
    }

    $ch = curl_init($url);
    curl_setopt_array($ch,$options);
    return $ch;
}