for 1 or 2 downloads it is quite normal to see those players not go on and deposit. I do feel for you as you are close to earning revenue.
I would go to those to the casino(s) which you have received a player registration and see you if can get some exclusive promotion for a trial period and I would look to see how you are driving traffic and maybe change how you are driving traffic to your sites. I would also just focus on blackjack content on your blackjack site.