如何将IPv6代理与php curl结合使用?

我正在尝试将IPv6代理与php CURL结合使用:

    self::$rCh = curl_init();
    curl_setopt( self::$rCh, CURLOPT_RETURNTRANSFER, true );
    curl_setopt( self::$rCh, CURLOPT_TIMEOUT, 30 );
    curl_setopt( self::$rCh, CURLOPT_CONNECTTIMEOUT, self::iTimeout );
    curl_setopt( self::$rCh, CURLOPT_USERAGENT, 'Mozilla/5.0 (Windows; U; 
Windows NT 5.1; en-US; rv:1.8.1.13) Gecko/20080311 Firefox/2.0.0.13' );
    curl_setopt( self::$rCh, CURLOPT_SSL_VERIFYHOST, 0 );
    curl_setopt( self::$rCh, CURLOPT_SSL_VERIFYPEER, 0 );
    curl_setopt( self::$rCh, CURLOPT_POST, 0 ); 
    curl_setopt( self::$rCh, CURLOPT_PROXY, 'a123:b123:123::1' );
    curl_setopt( self::$rCh, CURLOPT_PROXYPORT, 12345 );
    $sPage = curl_exec( self::$rCh );

无法解析代理“a123”

非常感谢。