Send costum variable

I think I need your help guys. I would say I have a much experience in Icinga but this problem is freacking me out.

    In my servers.conf I have defined this.
        object HostGroup "department" {
      display_name = "department"
      vars.sparte = "demartment"
      vars.responsible = "user1"
      vars.techdataowner = "user2"

object Host "servername" {
  import "generic-host"
  address = "ipaddress"
  a few more vars and things
   vars.applications = ["applicationname"]
  groups = ["department"]

In my notificationcommand.conf I have this one:

  object NotificationCommand "msend-service" {
    import "plugin-notification-command"
    command = [
    env += {
      NOTIFICATIONTYPE = "$notification.type$"
      SERVICEDESC = "$$"
      HOSTALIAS = "$host.display_name$"
      HOSTADDRESS = "$address$"
      SERVICESTATE = "$service.state$"
      SERVICESTATETYPE = "$service.state_type$"
      LONGDATETIME = "$icinga.long_date_time$"
      SERVICEOUTPUT = "$service.output$"
      HOSTDISPLAYNAME = "$host.display_name$"
      SERVICEDISPLAYNAME = "$service.display_name$"
      SERVICEPERFDATA = "$service.perfdata$"
      RESPONSIBLES = "$host.vars.responsible$"
      HOSTENV = "$host.vars.environment$"
      APPLICATION = "$host.vars.applications$"
      SPARTE = "$host.vars.sparte$"

But when I get an Mail the value “SPARTE” and “responsible” is empty. How to I get this values.
I have tried: host.vars.sparte; hostgroup.vars.sparte;; and nothing worked.

Thanks for your help

As far as I am aware you can’t have custom variables in host groups - custom variables can only be applied to hosts and services.

What @0xliam says is correct.

I would suggest you create a host template for each department and define the variables there.
Then import the template on you host and it will have the variables ready to be used by the notification ommand.