PHP Check for NULL

Here is the below Code:

$query = mysql_query("SELECT * FROM tablex");

if ($result = mysql_fetch_array($query)){

    if ($result['column'] == NULL) { print "<input type='checkbox' />"; }
    else { print "<input type='checkbox' checked />"; }
}

If the values are NOT NULL i still get the uncheked box. Am i doing something wrong from above, shoudnt $result['column'] == NULL work?

Any Ideas?