Since my cousin won big in Powerball, we’ve been buying tickets like crazy! However there are somethings I don’t understand about this.

OK, so I learned that they draw for Powerball on Wednesdays and Saturdays at 10:59 p.m.

I go here every Thursday and Sunday to check my numbers. I set it to go back a year, because people have 365 days to claim their money.
So far, every ticket I have appears to hit on $4.00 at some point in the last year, sometimes more than once, and I don’t understand that. Are they winners or not?
For example, I have a ticket that has the numbers:
12 28 30 31 41 23(pb). The drawing date on the ticket is Dec 6, 2014.
If you plug them in it shows a hit on 9/17/14, 6/11/14 and 1/1/14. But when I ran it by the clerk I bought it from, it wasn’t a winner.

Can someone explain this?