User access based on index

Hi, I want to set up various user roles to users in my splunk instances. Like Users from Group A should only have access to index A and So on. I tried 1. creating a new role called UserGroupA and add the index A to the role and adding the inherited parent as user role. 2. Cloned user role and restrict the index to index A. but none of this worked for me. Note : but if i restrict indexex to the role User without any additional roles added, then its worked. but my usecase is to set up multiple roles based on index and allow users to access only the index results and Dashboards.. Did I missing something? Thanks