اين المشكل في هذا الكود php وهو تسجيل عضو جديد وحفظه في القاعدة

Register

<center>
<form action="" method="post" >  
<table>
<tr><td>your name:</td><td><input type="text" name="username"/></td></tr>
<tr><td>your password:</td><td><input type="password" name="password"/></td></tr>
<tr><td>your age:</td><td><input type="text" name="age"/></td></tr>
<tr><td>your email:</td><td><input type="text" name="email"/></td></tr>
<tr><td>your country:</td><td><input type="text" name="country"/></td></tr>
</table>
<hr/>
<input type="submit" value="register" name="submit" />
</form>
</center>

<?php
$usernam=$_POST['username'];
$password=$_POST['password'];
$age=$_POST['age'];
$email=$_POST['email'];
$country=$_POST['country'];


if ($_POST['submit']){
if ($username!='' &&$password!=''&&$age!=''&&$email!=''&&$country!=''){

$connect=mysql_connect("localhost","root","root");
mysql_select_db("register");
$query=mysql_query("INSERT INTO rg VALUES('$username','$password','$age','$email','$country')");    
if ($query){
    echo "thank you for register";
    }

else{
    echo "error";
    }  
                                            }
else{
    echo "register please";
}
}


?>