Login to Google with PHP and Curl, Cookie turned off?

I have this code for logging into Google using Simple DOM Parser with curl. I've tried adding in the cookiejar file, but to no avail. I keep getting the message:

Your browser's cookie functionality is turned off. Please turn it on.

Any idea on how to solve this?

Here's my code for reference:

$html = file_get_html('https://accounts.google.com/ServiceLogin?hl=en&service=alerts&continue=http://www.google.com/alerts/manage');

//... some code for getting post data here

$curl_connection = curl_init('https://accounts.google.com/ServiceLoginAuth');
curl_setopt($curl_connection, CURLOPT_CONNECTTIMEOUT, 30);
curl_setopt($curl_connection, CURLOPT_USERAGENT, "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)");
curl_setopt($curl_connection, CURLOPT_RETURNTRANSFER, true);
curl_setopt($curl_connection, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($curl_connection, CURLOPT_FOLLOWLOCATION, 1);
curl_setopt($curl_connection, CURLOPT_COOKIEJAR, COOKIEJAR);
curl_setopt($curl_connection, CURLOPT_COOKIEFILE, COOKIEJAR);
curl_setopt($curl_connection, CURLOPT_HEADER, true);  
curl_setopt($curl_connection, CURLOPT_RETURNTRANSFER,1);
curl_setopt($curl_connection, CURLOPT_CONNECTTIMEOUT, 120);
curl_setopt($curl_connection, CURLOPT_TIMEOUT, 120);
curl_setopt($curl_connection, CURLOPT_POSTFIELDS, $post_string);

$result = curl_exec($curl_connection);
curl_close($curl_connection);

echo $result;