Authentication fails though the password is correct

I have a linux 7.7 machine which is integrated to Windows Active Directory. Also I have a local user "appuser" in the server for managing the application. While I switch to appuser, I am getting "su – Authentication Failure" Error. And in the /var/log/secure I get the below message.

su: pam_sss(su-l:auth): received for user appuser: 10 (User not known to the underlying authentication module)

How can I fix this?