[Plugin: WP eBay Ads] Call to undefined function: simplexml_load_file()

Here is the error message i get

Fatal error: Call to undefined function: simplexml_load_file() in /home/content/r/o/n/ront1963/html/mrwrestling2/wp-content/plugins/wp-ebay-ads/shortfunctions.php on line 188

http://wordpress.org/extend/plugins/wp-ebay-ads/