I don't know where to find out the error. the plugin just doesn't work after I install. I will try to figure it out and report it to Suresh.
about 1.8, I checked the github 1.8 branch, looks the db and points calculation is still current logic without comment out. not sure when will it be released as planned. hope they are doing offline dev.
I will use NoahY plugin first, at least it insert record into qa_uservotes table, which should be the final way to go. and hope new 1.8 will be release soon with comment vote feature.