How to make django comment model field No site required

I am using django-threadedcomments from ericflo on github. This application simply extends the scope of django's own comments. I am facing the same issue with both structures. I keep getting the mysql related error that site_id cannot be null. In my comments I do not use the "Site" field. I tried to expand the comment model with my own site, both empty and null, but I still get the same error. What is the proper way to repeal this requirement? Thanks

I tried:

class Comment(Comment):
    site=models.ForeignKey(Site,null=True,blank=True)