Why users are getting "Permission denied" error while creating files in its home directory in Red Hat Enterprise Linux ?

Issue

• NFS server and client are integrated with active directory and users home directories are exported and mounted through autofs in client system. When user try to create files in its home directory it says "Permission denied"

Server:

# vim /etc/exports 
/home *(rw,sync,no_root_squash) 

Client:

$ cat /etc/auto.home 
ADuser  NFSServer:/home/ADuser 

$ touch testfile 
touch: cannot touch `testfile': Permission denied