Why wptreehouse_username variable doesn't get saved in my case?

Here is the PHP code related to this from the main plugin file

$plugin_url = WP_PLUGIN_URL . '/wptreehouse-badges'; $options = array();

function wptreehouse_badges_options_page() {

if( !current_user_can( 'manage_options') ) {
    wp_die( 'You do not have sufficiant permissions to access this page!!!' );
}
global $plugin_url;
global $options;

if( isset( $_POST['wptreehouse_form_submitted'])) {
    $hidden_field= esc_html( $_POST['wptreehouse_form_submitted'] );
    if( $hidden_field == "Y") {
        $wptreehouse_username = esc_html( $_POST[ 'wptreehouse_username' ] );


        $options[ 'wptreehouse_username'] = $wptreehouse_username;
        $options[ 'last_updated' ]        = time();

        update_option( 'wptreehouse_badges', $options );

    }
}

$options = get_option( 'wptreehouse_username' );
if( $options != '' ) {
    $wptreehouse_username = $options[ 'wptreehouse_username' ];
}

require( 'inc/options-page-wrapper.php' );

}

And here is the HTML Form

<form name= "wptreehouse_username_form" method="post" action=""> <input type="hidden" name="wptreehouse_form_submitted" value= "Y"/> <table class="form-table"> <tr> <td> <label for= "wptreehouse_username">Treehouse Username</label> </td> <td> <input type="text" value="" class="regular-text" placeholder= "Username*" name="wptreehouse_username" id= "wptreehouse_username"/> </td> </tr> </table> <input class="button-primary" type="submit" name="wptreehouse_username_form" value= "save" /> </form>

Can anyone find my mistake and help me to identify really I what I was doing wrong?

Thank in advance