Cannot get tty name


I am trying to use wall command from with in the snap to broadcast message to all active terminal users on some event, unfortunately I am not able to access the tty . Can any one throw some light on what needs to be done to fix the problem ?

Here is the logs and error message .

$ sudo service-x.wall --help

 wall [options] [<file> | <message>]

Write a message to all users.

 -n, --nobanner          do not print banner, works only for root
 -t, --timeout <timeout> write timeout in seconds

 -h, --help     display this help and exit
 -V, --version  output version information and exit

For more details see wall(1).
$ sudo service-x.wall "Namaskara"
wall: cannot get tty name: Success

Apparmor logs

= AppArmor =
Time: Jul 19 14:50:32
Log: apparmor="DENIED" operation="open" profile="snap.service-x.wall" name="/run/utmp" pid=10055 comm="wall" requested_mask="r" denied_mask="r" fsuid=0 ouid=0
File: /run/utmp (read)
* adjust program to use $SNAP_DATA
* adjust program to use /run/shm/snap.$SNAP_NAME.*

Additional info

$ snap version
snap    2.33.1
snapd   2.33.1
series  16
kernel  4.4.0-122-generic