zabbix trigger on changed values

[03:37:20] root@simba:[/etc/zabbix]
# zabbix_get -s 192.168.1.51 -k redis[llen,storeapp:failed]
525
[05:19:44] root@simba:[/etc/zabbix]
# zabbix_get -s 192.168.1.52 -k redis[llen,storeapp:failed]
1470

changed trigger for failed jobs:

{redis.host:redis[llen,storeapp:failed].change()}<>0

so it will fire up when Items in Failed Queue is changed, not related on how many items we do have in queue.