admin login error

[meatyhotpants]

hi hows it going. having a problem with part 28 on your Developing a Dynamic Website 2014 Series. hope this has not been posted before, first time on github.com. on the admin login page I get this error. Warning: mysqli_num_rows() expects parameter 1 to be mysqli_result, boolean given in C:\xampp\htdocs\webfolio\dynamic\admin\login.php on line 15.

<?php

Start Session: session_start();

Database connection: include('../config/connection.php');

if ($_POST) {

$q = "SELECT * FROM users WHERE email = '$_POST[email]' AND password = SHA1('$_POST[password]')";
$r = mysqli_query($dbc, $q);

if(mysqli_num_rows($r) == 1) {

    $_SESSION['username'] = $_POST['email'];
    header('Location: index.php');

    }

}

hope i have posted this right. thinks

[meatyhotpants]

this may sound daft but could it be that I'm not putting in the correct password lol

[thedigicraft]

Haha it could be. I don't see anything off here.