Thank you so much!
The error after I made 50 events live is 'BAD REQUEST'.
Here is the whole error description.
{u'error': u'BAD REQUEST',
u'error_description': u'Error publishing event',
u'status_code': 400}
I tried to manually make events live after I met this error, and it failed too. The error shows on the website is: Whoops! We can't make your event live right now. Please try again later.
Thanks!