Summary:
The RPS (DKP) sub site of the forum was missing the top navigation menu.
Cause:
Server Side:
EQDKP has not yet been officially updated for PHP5 compatibility.
Fix:
eqdkp_plugins.php
651 $menu_array = array_merge($menu_array, $plugin_array[$plugin_code]);
changed to
651 $menu_array = array_merge((array)$menu_array, (array)$plugin_array[$plugin_code]);