since this seems to be a rockttheme template, tehn it is most probably a rocketthem plugin that you've installed. Disable the rockettheme plugins that you have till the comment system starts to work, then enable them one by one till it breaks again. Then you'll know which plugin exactly does that. I don't remember the name of the plugin, but once you know which one it is - go in it and there was a "legacy support" setting in it. Enable/disable it and the comment system will most probably work again after that.