Mimicing a html (POST) call from flash

programming flash
1

I’m basically trying to re-create a HTML link in flash that will allow me to log in to my forums. Here’s the HTML version:

<form action="blah.com/forums/ucp.php?mode=login" method="post">
    <fieldset>
        <label for="username">Username:</label>&nbsp;
        <input type="text" name="username" id="username" size="10" title="Username" />
        <label for="password">Password:</label>&nbsp;
        <input type="password" name="password" id="password" size="10" title="Password" />
        <input type="submit" name="login" value="Login" />
    </fieldset>
</form>

and the AS3 version:

	var req:URLRequest = new URLRequest("http://blah.com/forums/ucp.php?mode=login");
	var vars:URLVariables = new URLVariables();
	
	vars.username = USERNAMESTRING;
	vars.password = PASSWORDSTRING;
	req.data = vars;
	req.method = URLRequestMethod.POST;	
	navigateToURL(req);

It successfully loads the new page but the login doesn’t go through, any ideas?