Placement of the robots.txt file
The robots.txt file must reside in the root of the domain and must be named "robots.txt". A robots.txt file located in a subdirectory isn't valid, as bots only check for this file in the root of the domain. For instance, http://www.example.com/robots.txt is a valid location. But, http://www.example.com/mysite/robots.txt is not. If you don't have access to the root of a domain, you can restrict access using the Robots META tag.