Problem only while using require_once() within functions.php

I use add_theme_page() within my child theme’s functions.php implemented something like this…

// other functions located here that create a custom options page in the Dashboard.
// THIS IS NOT A FILE PATH ISSUE ->  THE CUSTOM PAGE IS CREATED IN BOTH CASES.

function my_menu() {
    ...
    if ( 'save' == $_REQUEST['action'] ) {
        echo '<meta http-equiv="refresh" content="0;url=themes.php?page=functions.php&saved=true">';
        die;
    }
    add_theme_page(...)
}

add_action('admin_menu', 'my_menu');

As per the WordPress docs:

NOTE: If you’re running into the »You do not have sufficient
permissions to access this page.« message in a wp_die() screen, then
you’ve hooked too early. The hook you should use is admin_menu.

This is exactly the error I’m getting right after saving my options. However, I’ve used the correct hook as recommended.

This error only occurs if I move my function into a new file and do use a require_once within funtions.php. I was organizing my code as per this answer.

require_once('includes/functions-theme-options.php');

Why does this break simply by moving the function into an external file? I thought maybe it had to do with placement, but the require_once() is in the exact position where the original code was placed.

• When the code is inside of functions.php, it works fine.

• When the code is moved to an external file and reference with require_once(), it breaks (error messages upon save as per the referenced docs above).

Obviously, for now, I’m keeping it within function.php, but maybe somebody can explain why it’s breaking when I move it.

EDIT

This is not a file path issue. Every file referenced by require_once() is being found and included. The problem seems to be how it’s being executed.

Please read this answer: https://wordpress.stackexchange.com/a/1406/11092

EDIT 2 – revised 1/16/13

This is a stripped down version that was verified to fully demonstrate the issue. This code constructs a submenu page under “Appearance” called “Theme Options”. When you click the “Save Options” button, the page is supposed to reload and show a “your-theme settings saved” message. However, instead it shows the WordPress error page, “You do not have sufficient permissions to access this page.” Simply moving the last function into functions.php clears up this permissions issue. I would like to know why and how I can fix it.

in functions.php file:

<?php

require_once('includes/functions-test.php');

in my child-theme-directory, includes/functions-test.php file:

<?php

$themename = wp_get_theme();

function mytheme_admin() {

    global $themename;

    if ( $_REQUEST['saved'] ) echo '<div id="message" class="updated fade"><p><strong>'.$themename.' settings saved.</strong></p></div>';

    ?>

    <div class="wrap">
        <h2><?php echo $themename; ?> Options</h2>
        <div style="border-bottom: 1px dotted #000; padding-bottom: 10px; margin: 10px;">Options specfic to this theme.</div>
        <form method="post">
            <p class="submit">
                <input name="save" type="submit" class="button button-primary" value="Save Options" />    
                <input type="hidden" name="action" value="save" />
            </p>
        </form>
    </div>

<?php               
}


function wp_initialize_the_theme_load() {
    if (!function_exists("wp_initialize_the_theme")) { 
        wp_initialize_the_theme_message();
        die;
    }
}

add_action('admin_menu', 'mytheme_add_admin');


/*  move only the following function to 'functions.php' and the problem is gone
__________________________________________________________________________*/ 

function mytheme_add_admin() {
    global $themename, $shortname;  
    if ( $_GET['page'] == basename(__FILE__) ) {    
        if ( 'save' == $_REQUEST['action'] ) {
            echo '<meta http-equiv="refresh" content="0;url=themes.php?page=functions.php&saved=true">';
            die;
        } 
    }
    add_theme_page($themename." Options", "Theme Options", 'edit_theme_options', basename(__FILE__), 'mytheme_admin');
}