Any app that is not created/built by RIM is considered third party app, regardless if it is listed in Appworld or not. Free WhatsApp Messenger - Download WhatsApp Messenger - Free Apps from BlackBerry App World
vs. Free BlackBerry Bridge - Download BlackBerry Bridge - Free Apps from BlackBerry App World
By Research In Motion Limited
Yeah something is preventing BAS to connect to URL to download XML file such as outbound port filtering (port 443), organization disallows download of xml files etc...