Flash AS3 class - actionscript-3

Question

So I'm new to Flash and I'm currently following a tutorial about login and registration.
The tutorial that I followed has an external AS file just like this :
where I type the name of the class in the space given. So far, when I run the program, it gives me the correct output.
Now here comes my problem. I've made some modifications to the way it references(?) the class, which in this case, I export the class just like this in the symbols properties. And now, the code won't work and I've been trying to figure this out for about 5 hours already and I can't seem to get it done.
Here's the image of me adding the class in the symbols properties :
And here is my login class :
package {
/*
always extend a class using movieclip instead of sprite when using flash.
*/
import flash.display.MovieClip;
import flash.events.*;
import flash.net.*;
import flash.text.*;
/*
create our class
*/
public class login extends MovieClip {
public function login(): void {
/*
buttonMode gives the submit button a rollover
*/
login_button.buttonMode = true;
/*
what this says is that when our button is pressed, the checkLogin function will run
*/
login_button.addEventListener(MouseEvent.MOUSE_DOWN, checkLogin);
/*
set the initial textfield values
*/
username.text = "";
password.text = "";
}
public function checkLogin(e: MouseEvent): void {
/*
check fields before sending request to php
*/
if (username.text == "" || password.text == "") {
/*
if username or password fields are empty set error messages
*/
if (username.text == "") {
username.text = "Enter your username";
trace(success);
}
if (password.text == "") {
password.text = "Enter your password";
}
} else {
/*
init function to process login
*/
processLogin();
}
}
public function processLogin(): void {
/*
variables that we send to the php file
*/
var phpVars: URLVariables = new URLVariables();
/*
we create a URLRequest variable. This gets the php file path.
*/
var phpFileRequest: URLRequest = new URLRequest("php/controlpanel.php");
/*
this allows us to use the post function in php
*/
phpFileRequest.method = URLRequestMethod.POST;
/*
attach the php variables to the URLRequest
*/
phpFileRequest.data = phpVars;
/*
create a new loader to load and send our urlrequest
*/
var phpLoader: URLLoader = new URLLoader();
phpLoader.dataFormat = URLLoaderDataFormat.VARIABLES;
phpLoader.addEventListener(Event.COMPLETE, showResult);
/*
now lets create the variables to send to the php file
*/
phpVars.systemCall = "checkLogin";
phpVars.username = username.text;
phpVars.password = password.text;
/*
this will start the communication between flash and php
*/
phpLoader.load(phpFileRequest);
}
public function showResult(event: Event): void {
/*
this autosizes the text field
***** You will need to import flash's text classes. You can do this by adding:
import flash.text.*;
...to your list of import statements
*/
result_text.autoSize = TextFieldAutoSize.LEFT;
/*
this gets the output and displays it in the result text field
*/
result_text.text = "" + event.target.data.systemResult;
trace(success);
}
}
}
Edit :
Here is the picture where the base class just disappears :
Thanks for the help.