[HỎI] Vì sao biến $_POST[''submit''] không được nhận

<?PHP
$page_tittle="Dang Ki";
include ('./header.inc');
if (isset($_POST['submit']))
{
if (strlen($_POST['name']) >0)
{
$name=TRUE;

} else
{
$name=FALSE;
echo "<p>Ban chua nhap ten</p>";
}
if (strlen($_POST['username'])>0)
{
$username=TRUE;
} else
{
$username=FALSE;
echo "<p>Ban chua nhap Username</p>";
}
if (strlen($_POST['email']) > 0)
{
$email=TRUE;
} else
{
$email=FALSE;
echo "<p>Ban chua nhap email</p>";
}
if (strlen($_POST['password1']) > 4)
{
if ($_POST['password1'] == $_POST['password2'])
{
$password = TRUE;
} else
{
echo "<p>Mat ma xac nhan ko trung</p>";
}
} else
{
$password = FALSE;
echo "Ban chua nhap mat ma hoac mat ma it hon 4 ki tu";
}
if ($name && $username && $email && $password)
{echo "Ban da dang ki thanh cong";}
else
{echo "Hay thu lai lan nua";}
} else
{
?>
<form action="<?PHP echo $_SERVER['PHP_SELF'];?>" method="post">
<fieldset> <legend>Hay nhap thong tin cua ban</legend>
<p><b>Ten:</b> <input type="text" name"name" size="40" maxlength="40" /> </p>
<p><b>Username:</b> <input type="text" name"username" size="40" maxlength="30" /> </p>
<p><b>Email:</b> <input type="text" name"email" size="50" maxlength="60" /> </p>
<p><b>Password:</b> <input type="password" name"password1" size="50" maxlength="20" /> </p>
<p><b>Xac nhan:</b> <input type="password" name"password2" size="50" maxlength="20" /> </p>
</fieldset>
<div align="center"> <input type="submit" name"submit" value="submit" /> </div>

</form>
<?PHP
}
include ('./footer.inc');

?>