After upgrading an indexer (also being used as a search head) from Splunk 6.0 to 6.3.2, why is no data showing in the dashboard?

Hi, I have an indexer which is also being used as a search head. It was Splunk version 6.0 and all the data was showing in the dashboard, but when I upgraded it to 6.3.2 , no data is showing up. Even If I forward any new input from the forwarder, it is not showing up in the "Indexer". Please help me out to fix this issue !!