Cisco Web Communicator dll plugin available to use in html page but not in FF extension/addon

Question

I'm scratching my head on an issue with Firefox accessing a dll file in an extension. I am using version 3.0.6. The functions of the dll is handled through a cwic.js file, which can be referenced here. The functions of registering a phone, making a call, etc can all be accessed and works when I make a simple html page with JS and load it with Firefox. However, once I try and have functionality in an extension toolbar it fails. I'm using Firefox 24.

extension.xul

<overlay xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
     xmlns:html="http://www.w3.org/1999/xhtml">

             <!--I have some more code here-->

<!--Init Plugin-->

<window id="main-window">
  <vbox collapsed="true">
      <html:object type="application/x-ciscowebcommunicator" heigth="1" width="1" id="ciscowebcommunicator" 
                   style="visibility:hidden;">
      </html:object>
      <html:div id="call-container" />
  </vbox>
</window>

install.rdf contains this line

<em:unpack>true</em:unpack>

My extension script

$("#call-container").cwic('init', {
    ready: function(){
    /* DISABLE CERTIFICATION */
    if ((jQuery(document).cwic('about').capabilities.certValidation)) {

        jQuery(document).cwic('disableCertValidation');            
    }
        jQuery(this).cwic('registerPhone', {  //values below are referenced elsewhere
            user: username, 
            password: password,
            mode: 'DeskPhone',
            cucm: 'CUCM_IP',
            success: function() {
                alert('logged in!');
            }
        });
    }
});

Error I get back

[12:47:07.420] "[cwic] 22/07/2014 12:47:07.419 Plugin not available"

I'm not sure why it wont work in an extension. I used alert() to check if the block runs, and it should. Would appreciate any help.