how to set up variables in iCall?

I set up iCall to collect tcpdump at status "session status forced disabled"

alert:

alert POOL-MEMBER-DOWN "Pool (.*?) member (.*?):(.*?) session status forced disabled" {     exec command="tmsh generate sys icall event tcpdump context none"    }

script:

modify script tcpdump {
        app-service none
        definition {
            set date [clock format [clock seconds] -format "%Y%m%d%H%M%S"]
        exec tcpdump -ni any -s0 -w /var/dmp/${date}.dmp -c 100  host  and port 
        }
        description none
        events none
    }

That works for one server. How set up this script for other servers but use one alert? I tried to other values for variables, but still don't work.