Remove Nat Sessions on a specific event

[rextended]

I use this in both the up and down actions of a netwatch entry that pings my next hop gateway:

/ip firewall connection remove [find];
:log info ("Cleared-Connecitons");

DO NOT WORK as expected

read this:
http://forum.mikrotik.com/t/script-to-clean-firewall-connections-after-public-ip-changes/135275/5