Some of below are not confirmed but are intuitive one.
1. add "ddns-update-style ad-hoc;" as the first line
2. harryson should not have the address overlapping with 'range dynamic-bootp'
3. 'netbios-name-servers' should have the address which belongs to the net 188.8.131.52; netbios is not routable so it may cause a problem in future
4. you wrote "for one of my subnetwork" - all the subnets should be specified; I believe you have got the respective message from dhcp daemon (see logs)
The rest looks ok, so if it still doesn't work I think it is the firewall problem.