1. Clear your flash cookies. You can do that by going here:
Advertisers might also be tracking your flash cookies, therefore you need to clear them as well as regular cookies before doing an offer.
Click delete all
2. Log in to your email address before doing the offer, or at least sometimes within the day you do the offer. Advertisers like active emails, if you haven't logged into the email address you are using for a month or a couple weeks the offer might not approve because the advertiser will see the email as inactive.