ob_start() redirects my wp-admin

Hi,

I’m currently working on a custom login.
I found this online and try to work with it.

I ran into a little problem that said: Headers allready sent…
I found the ob_start(); function:

function app_output_buffer() {
	ob_start();
}
add_action('init', 'app_output_buffer');

This does do the trick. My users can now login to the website.
However, if I try to login to my wp-admin the page redirects me to the login page on the website.

Here is my code on the login page:

<?php
	if($_POST) {

		global $wpdb;

		//We shall SQL escape all inputs
		$username = esc_sql($_REQUEST['username']);
		$password = esc_sql($_REQUEST['password']);

		$login_data = array();
		$login_data['user_login'] = $username;
		$login_data['user_password'] = $password;

		$user_verify = wp_signon( $login_data, false ); 

		if ( is_wp_error($user_verify) )
		{
			echo "<span class=\"error\">Invalid username or password. Please try again!</span>";
		} else
		{
			echo "<script type=\"text/javascript\">window.location='". get_bloginfo('url') . "/home-extranet'</script>";
			exit();
		}
	}
?>
		<form id="login" name="form" action="<?php echo home_url(); ?>/login/" method="post">
			<input id="username" type="text" placeholder="Username" name="username">
			<input id="password" type="password" placeholder="Password" name="password">
			<input id="submit" type="submit" name="submit" value="Submit">
		</form>

Here is the page that it redirects to if login is approved:

<?php
 if(!is_user_logged_in()) {
wp_redirect(home_url() . '/login' );
}else{
  ?>
	<h1><?php the_title(); ?></h1>
<?php }?>

Once again if the usere logs in via the website there is no problem, but if I try to login to my wp-admin it redirects to de login on my website.

Any ideas???? I’m kinda stuck…

M.