Put your robots.txt in the root directory of each site - in the same directory as your main "index.html" page. Robots will look for it there, and nowhere else. Then, validate your robots.txt files here [searchengineworld.com].
Thank you Jim! One thing, put the robots.txt in each domain root is not effective as i am using .htaccess file with "rewrite" index.php orders. Put the robots.txt file just in the serverīs root can help?