To clarify, this error occurs because multiple versions of jQuery are being loaded on the page. Armadillo functions are indeed present and accessible, but are “attached” to a different version of jQuery loaded at the beginning of the page as part of the Stacks plugin (which is superseded by the theme’s version of jQuery, which is loaded at the very bottom of the page).
For other’s who may be encountering a similar issue, you may be able to resolve it by adding this snippet of javascript to the Javascript area of RW’s Code section:
jQuery.noConflict(true);
Hope this helps.