Well... after 3 emails sent to Linkshare, I finally got an answer today:

"At the time you wrote your email, you were just approved into the merchant's program. The system needs to time synchronize up with your acceptance information. The links should be working now. We apologize for any inconvenience this may have caused you."

hmmm... then *linkshare* staff, you should rephrase the text you use informing affiliates about their immediate acceptance.

Andy, thanks for responding. I already sent you a sale ;-)