I'm getting a 500 Internal Server Error when I click on checkout each time this module is Enabled. I would like the ability to be able to ship using a good Fedex module. I'm using Numinix Fedex XML module and one it is set to true under enable I'm getting this error under the cache logs:

Code:
[17-Sep-2013 10:49:03 America/Los_Angeles] PHP Fatal error:  Uncaught exception 'Exception' with message 'String could not be parsed as XML' in /home/gunsan6/public_html/includes/modules/shipping/fedexground.php:377
Stack trace:
#0 /home/gunsan6/public_html/includes/modules/shipping/fedexground.php(377): SimpleXMLElement->__construct('')
#1 /home/gunsan6/public_html/includes/modules/shipping/fedexground.php(184): fedexground->getPrice('GROUNDHOMEDELIV...')
#2 /home/gunsan6/public_html/includes/classes/shipping.php(136): fedexground->quote('')
#3 /home/gunsan6/public_html/includes/modules/pages/checkout_shipping/header_php.php(185): shipping->quote()
#4 /home/gunsan6/public_html/index.php(47): require('/home/gunsan6/p...')
#5 {main}
  thrown in /home/gunsan6/public_html/includes/modules/shipping/fedexground.php on line 377
Why would I be getting something like this and is there anything I can do to fix this?