PDO: What's wrong with this block of code?

PDO: What's wrong with this block of code?

Feeling a little stupid to ask such a question, but this code block is
driving me crazy.
function __construct() {
$db = new db();
$this->db = $db->pdo;
}
function getEmployeeDetails() {
$eid = $this->db->quote($this->eid);
try {
$sql = $this->db->query("
SELECT email, cnumber
FROM employees
WHERE EID = $eid
");
$r = $sql->fetch();
$this->email = $r[0];
$this->cnumber = $r[1];
}
catch (PDOException $e) {
throw new Exception("failed");
}
}
It doesn't throw an exception but fails inside the try block - "Call to a
member function fetch() on a non-object".
var_dump of the statement object returns 'false'. Why?
I've tried running the query independently, inside MySql. It returns 1 row.