when i submit nothing happens, please help! im a newbie in php 
[php]
Log in
| Username: | |
| Password: | |
| Classification: |
Admin Faculty Student |
</form>[/php]
validation.php
[php]
if (isset($_POST[‘submit’])) {
$username = $_POST[‘username’];
$password = $_POST[‘password’];
$selected_key = $_POST[‘class’];
$selected_val = $class[$_POST[‘class’]];
if ($selected_val=="student"){
$sql1 = mysql_query("SELECT * FROM student WHERE username='".$username."' AND password='".$password."' ");
if (mysql_num_rows($sql2) == 1 ) {
$row = mysql_fetch_assoc($sql);
header("Location: home.php");
}
else{
echo "Incorrect login details. Please try again";
}}}[/php]