SQL query issue again

$sql = "SELECT item FROM survey_results WHERE user_email = ? AND taxyear = ? AND item_type='AC' ";  //only look at Activities
$query2 = $this->db->query($sql, array($employee_email, $taxyear));

This query seems to work fine when I use [email protected] and 2017.

But when I use [email protected] and 2017 it doesn't find anything.  Could there be a problem with using an "@" in the string? If true, why would @yahii.com work? I originally had the taxyear as an integer. I changed that to a varchar. taxyear varchar(11) utf8mb4_bin. Could it be that my '2017' is only four chars, not 11? 

proof that an old dog can learn new tricks