In my configuration there is also
/ip firewall filter
add chain=input comment=Ip-Sec-ESP protocol=ipsec-esp
add chain=input comment=IP-Sec-AH protocol=ipsec-ah
on both routers. Maybe this will help? Anyway, you should read the topic http://forum.mikrotik.com/t/help-with-ipsec-nat-traversal/58597/1 and delete this one, because they are similar.