In case you are not making much headway even after repeated attempts, make sure to check out the following

1. Make sure that you are using the zipcode that corresponds to the latest address. Searching a person who might have relocated  to another address is futile.
2. You will get only an abbreviated version of the roll for online search . Probably  the person you are looking for might have opted out of the list.
3. Electoral rolls list out people according to the constituencies.  Check  the boundary commission report to make sure that the constituency has not changed over the years.
4. Having checked all the essentials, you have a fair chance of finding someone with whom you have long lost contact.