The function itrader_CompareVersions is either implemented wrong or used wrong. There are two calls similar to this:
Code:
if(itrader_CompareVersions($vbulletin->options['templateversion'], '4.1.3') > 0)
If the version of VB is higher than 4.1.3, itrader_CompareVersions returns -1. But both if statements assume that it would return +1. The consequence is that the plugin tries to include functions_wysiwyg.php instead of class_wysiwygparser.php, but functions_wysiwyg.php has been removed from VB.
Due to this bug, users get a HTTP 500 if they rate a deal using the WYSIWYG editor.