Predictive member issue

ltm virtual namezabbix.none.com_80 {

destination 10.208.X.X:http
ip-protocol tcp
mask 255.255.255.255
persist {
    source_addr_60min {
        default yes
    }
}
pool namezabbix.pool_8080
profiles {
    tcp-lan-optimized { }
}

ltm persistence source-addr source_addr_60min {

defaults-from source_addr
map-proxies enabled
mask none
match-across-pools disabled
match-across-services disabled
match-across-virtuals disabled
mirror disabled
override-connection-limit disabled
timeout 3600

ltm pool namezabbix.pool_8080 {

load-balancing-mode predictive-member
members {
    10.216.X.X:webcache {
        priority-group 1
        session monitor-enabled
    }
    10.216.X.X:webcache {
        priority-group 2
        session monitor-enabled
    }
}
min-active-members 1
monitor http_200_response

ltm monitor http http_200_response {

defaults-from http interval 5 recv "HTTP/1.1 200 OK" send "GET / HTTP/1.1\nHost: \nConnection: Close\r\n\r\n" time-until-up 0 timeout 16