WooCommerce + Quickbooks POS Plugin Hosted at ZippyKid - repost

I'm hosting at ZippyKid a fresh WooCommerce install. I'm having fits trying to get a Quickbooks Point of Sale inventory plugin from 61Extensions to work. The Intuit WebConnector connects to WordPress fine. However, when inventory quantities on WP need adjusting from QBPOS, WebConnector always responds with ReceiveResponseXML Failed logs show that the XML is not well formed. The plugin developer has not been that helpful in resolving the issue. ZippyKid support has been fantastic, yet they do not know what they should be looking at to see if it is a server-side setting that is causing the XML to be improperly formed. I'm at the point of needing someone to dive in and help me fix this last little kog in the setup. I'm not married to the 61Extensions plugin, but it's mostly working except for this one portion. Ideally I'd like to fix this plugin instead of starting fresh. Looking for someone willing to take a look at the WP install and see if you can find where the problem is and try to resolve it. Here is a link to the plugin I'm using: [login to view URL]