ciao, ho un problema con una query insert:

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '=DATE_ADD(NOW(), INTERVAL , phone, cognome, cell' at line 1

la query è

Codice PHP:
$insertSQL = sprintf("INSERT INTO info (email, password, `expires`=DATE_ADD(NOW(), INTERVAL ".$credit['days']." DAY, phone, cognome, cell) VALUES (%s, %s, %s, %s, %s, %s)",       
GetSQLValueString($_POST['email'], "text"),                         GetSQLValueString(md5($password), "text"),                        GetSQLValueString($_POST['expires'], "date"),                                               GetSQLValueString($_POST['phone'], "text"),                        GetSQLValueString($_POST['cognome'], "text"),                                     GetSQLValueString($_POST['cell'], "text")); 
perchè quell'errore?