Well somnebody's links are working. I have had a few from joinups in the last month.
Jimbo regularly tops the Buddy Point Leader Board each month. As he doesn't sell (and only seems to buy using Buddy Points) they must all be from joinups. Love to know how he does it.
Unless you can watch someone register via your link then you can't say it isn't working. There are too many ways they can join without using your link or voiding your link if they have used it.