Help Needed on Views UI in Drupal 7
Your invaluable suggestion moved me for searching deeply in the relationship of Views UI and guess what? I solved the problem after the hours of study in Views UI. Here in this case there are two relations involved. The 2nd relation is involving the first one. This will not be possible to sort out if I didn't know how to turn on the SQL query in Views UI. This link also helped me.

Use of relationships (joins) in Views

Thanks You Nikhil!