Why do automount shares give "Permission denied" error?

Issue

• The auto.direct and the stacked mounts on client(shown below)

/parent                -rw                                      server1:/vol/parent \
  /child1              -ro                                      server1:/vol/child1 \
  /child2              -ro                                      server1:/vol/child2 \
  /child3              -ro                                      server1:/vol/child3

• All fail to work. Running automount in debug mode shows the following error message.

# automount -f -d -v

  mount_autofs_offset: can't create mount directory: /tmp/autoHUJvGG/child1, Permission denied

• None of the mounts work but mounting the volumes manually works.