Theme option page doesn’t save options

I am trying to practice adding theme options page using settings API but unfortunately the code i have written according to the codex doesn’t work properly. When i tested the code no errors generated but the pe_bannar_heading option can’t be saveed , So would you please help me find where the problem is in the following code

    <?php
    /*
    Plugin Name: Test option page
    Text Domain: test-option-page
    */

    function reg_settings(){
        register_setting('pe_theme_options','pe_theme_options');
        add_settings_section('pe_main_settings','Main Settings', '', __FILE__);
        add_settings_field('pe_bannar_heading', 'Bannar Heading:', 'pe_bannar_heading_setting', __FILE__, 'pe_main_settings');
    }

    add_action('admin_init','reg_settings');

    function pe_bannar_heading_setting(){ 

                $options = get_option('pe_theme_options');?>
                <input name="pe_bannar_heading" type="text" value="<?php if(isset($options['pe_bannar_heading'])) echo $options['pe_bannar_heading'] ?>"/>

            <?php }

    function pe_add_menu_page(){
                add_options_page('Theme Options', 'Theme Options', 'administrator', __FILE__ , 'display_options_page');
            }

    add_action('admin_menu','pe_add_menu_page');

    function display_options_page(){

                $options = get_option('pe_theme_options');?>
                <div class="wrap">
                    <h2>Yellow Blog Options</h2>
                    <form action="options.php" method="post" enctype="multipart/form-data">
                        <?php 
                            settings_fields('pe_theme_options');
                            do_settings_sections(__FILE__);
                            submit_button( 'Save Settings' );
                        ?>
                    </form>
                </div>  
    <?php   }