A Trusted Root Certificate is the top most certificate of the tree structure unless Trusted Root Certificate of certificate authority is installed digital signature certificate issued by certifying authority is not recognized by the browser. In India Root Certificate of approved and Trusted Certificate Authority are digitally signed by Comptroller of Certifying Authority. In order to make your Digital Signature Certificate work properly, One has to install Root Certificate of Comptroller Of Certifying Authority and also of certifying authority whose Digital Signature Certificate is bought by you namely-Tata Consultancy Services, Ncode Solution, Sify/Safescrypt, Emudhra.