[Threshold]

This happened with me too once, I have no idea why it wouldn't work. I updated the plugin, tried deleting it all and re-installing it, looked at the include and plugin version to make sure they matched, and I still got this annoying error for some weird, unexplainable reason. I can't remember how I fixed it though, make sure you're replacing your current include file with the new one that you've downloaded from the plugin's forum thread. Otherwise, try editing the include file and changing 26104 to 26105 and pray that it works.