I have cluster setup containing 1 load balancer address:
cluster
.. and multiple nodes:
node1
node2

I want to create a trigger on load balancer host, that indicates that all the nodes have failed.
So I navigate under cluster host and create new trigger with expression like that:

{node1:service_state[service].last(3)}

>0&

{node2:service_state[service].last(3)}

>0
...but this trigger is saved under the host that is described first it the trigger expression, not under the load balancer host.
So on this case under the node1.

And when trying to copy trigger to load balancer host, I get the following error:
Missing key "service_state[service]" for host "cluster"