Lets fix this.

In your admin/additional_customers_fields.php file,

move:

PHP Code:
  //----------------------------------------------------------------------------------
  //--- No customers are allowed (can't take any chances) ---
  //----------------------------------------------------------------------------------  
  
if (!$_SESSION['admin_id']) {
      
$messageStack->add_session(ENTRY_ADDITIONAL_CUSTOMERS_FIELDS_UNAUTHORIZED_ACCESS'warning');                       
      
zen_redirect(zen_href_link(FILENAME_ADDITIONAL_CUSTOMERS_FIELDS'''NONSSL'));
  } 
// End of if statement.
  
?> 
Then, find:

PHP Code:
<?php require(DIR_WS_INCLUDES 'header.php');
replace with:

PHP Code:
<?php require(DIR_WS_INCLUDES 'header.php');
  
//----------------------------------------------------------------------------------
  //--- No customers are allowed (can't take any chances) ---
  //----------------------------------------------------------------------------------  
  
if (!$_SESSION['admin_id']) {
      
$messageStack->add_session(ENTRY_ADDITIONAL_CUSTOMERS_FIELDS_UNAUTHORIZED_ACCESS'warning');                       
      
zen_redirect(zen_href_link(FILENAME_ADDITIONAL_CUSTOMERS_FIELDS'''NONSSL'));
  } 
// End of if statement.
  
?>
Should work now.