How can I put a sensor only for 1 hd?

Im trying to put a specific sensor on a single disk (my machine have multiple HD), my disk_full_perccent.conf have this configuration:
template: disk_full_percent
calc: $used * 100 / ($avail + $used)
units: %
every: 1m
warn: $this > 80
crit: $this > 90
repeat: warning 7200s critical 3630s
Well I already checked the documentation and I see that if you want to put an specific sensor for a disk you have to add some lines in health_alarm_notify.conf, I added this:
alarm_space = yes
alarm_space_gigabyte = 6.5
alarm_space_log = yes
alarm_space_log_clean = no
alarm_space_recursive = no
But never shows the alert, I need help to make this specific sensor.

Hi @Yisus

Check out the option chart labels. There is some more information here → Configure alerts | Learn Netdata