The visitors in your forum are not looking for the products, that is why you do not earn on your adsense
Bet your money on the Forum... Because: If the forum gets sucessful, you only need to moderate, and it will keep growing on its own. Whereas for the blog, you need to write good articles everyday, more so if it gets sucessful, and only a few bloggers are successful.. The key with Forums is to get Guests.. Lots of them.. I love forums that have a current stat that looks like Currently Active Users: 2000 (200 members and 1800 guests) The members are Ad Blind, but the guests sure aren't.. And you can create massive amounts of content using a forum once it has reached that tipping point.. It juts is difficult to take a forum to that level. Continue the blog only if you are a really good writer and can research real well...
me too but my blog is 1 year old and my forum is 3 monthes old I get 75% from blog but forums are just self building sites