Help getting custom stylechoose code to work

[Mark.B]

Some time ago, after much messing about, I managed to get the code in THIS thread to work on my live site.

What this does is change the style chooser dropdown (for members) so that instead of setting a cookie, it actually updates the user profile.

However, despite replicating the template code exactly using vB4-style variables, I can't get it to work. It seems to submit the form but redirects back to index.php instead of staying on the page it was on, but doesn't actually change the style. That suggests that the $show['member'] conditional is returning false, but even if I totally remove that conditional and just leave the code to be executed on submitting the form, it still does the same thing.

I've tried comparing the code with other files in vB4 and it seems correct, so I can't work out what's missing. I'm sure it's something simple.

Here's the contents of my file myprofile.php:

<?php
// ####################### SET PHP ENVIRONMENT ###########################
error_reporting(E_ALL & ~E_NOTICE);

// #################### DEFINE IMPORTANT CONSTANTS #######################
define('THIS_SCRIPT', 'myprofile');
define('CSRF_PROTECTION', true);

// ######################### REQUIRE BACK-END ############################
require_once('./global.php');

// ############################### start update options ###############################
if ($_POST['do'] == 'updateoptions')
{
    if ($show['member']){

        $vbulletin->input->clean_array_gpc('p', array('newstyleset'    => TYPE_INT));

        $userdata =& datamanager_init('User', $vbulletin, ERRTYPE_STANDARD);
        $userdata->set_existing($vbulletin->userinfo);

        // style set
        if ($vbulletin->options['allowchangestyles'] AND $vbulletin->userinfo['realstyleid'] != $vbulletin->GPC['newstyleset'])
        {
            $userdata->set('styleid', $vbulletin->GPC['newstyleset']);
        }

        ($hook = vBulletinHook::fetch_hook('profile_updateoptions')) ? eval($hook) : false;
        $userdata->save();
    }
    else {
         exec_header_redirect("../index.php?");
    }
}

// #############################################################################
$url = $_SERVER['HTTP_REFERER'];
exec_header_redirect($_SERVER['HTTP_REFERER']);

?>

And here's the code I'm using in the footer template to power the style chooser, this is basically an exact replication from the vB3 site but with the relevant compatibility changes for vB4:

<vb:if condition="$show['quickchooser']">
<vb:if condition="$bbuserinfo['userid']">
<form style="display: inline" action="myprofile.php" method="post" >
<input type="hidden" name="s" value="" />
<input type="hidden" name="do" value="updateoptions" />
<input type="hidden" name="securitytoken" value="{vb:raw bbuserinfo.securitytoken}" />
<select class="forumselector" name="newstyleset" id="sel_newstyleset"  onchange="this.form.submit()";>
<optgroup label="{vb:rawphrase quick_style_chooser}">
{vb:raw quickchooserbits}
</optgroup>						             
</select>
</vb:if>	
</vb:if>

I have wrestled with this one on and off for weeks and cannot fathom what is wrong.

Can anybody spot what needs changing? If pointed in the right direction I'm sure I'm savvy enough to sort it!