It's a little flakey because they have to sign up from the link you use. If they dont sign up, then come back on another browser or something later it doesn't count them.
The challenge is for 3 sign ups. No point requirements.
There should be a link that lists who has signed up for you.
This is the link I used:www.funtrivia.com/?ref=Nammage
This page says I have referred 4 people:http://www.funtrivia.com/refer_track.cfm
These are the people and dates listed (removed email names):
Users Signed Up From Your Referrals So Far
.hotmailom Shellaroo Signed up May 02 09
yahoo.com LoriPinkAngel Signed up Mar 28 14
.co.uk mrjason2 Signed up May 01 14
gmail.com bluecelt Signed up May 30 14
So, since it didn't work I have to do it again?
I don't think so.