IPDiscovery not working

Good morning everyone,

 Just finished setting up OCS Server and, to start using it, installed OCS Agent on the same VM where the server is. I have seen the data from the agent shows up on OCS Server (VM info, networks, disks, software, etc) but unfortunately ip discovery does not work.

 On Inventory/ipDiscover, there are only two hosts listed (which are actually the server - one line regarding the IPv4 interna156 server IP, and another line regarding the IPv6 server IP.

 I have even tried executing the ip-discovery script manually, but it always turns up empty:

ipdiscover-util.pl -p=ocs -d=dbname -u=username -h=localhost -net=192.168.156.0 -auto

########################
Starting scan of subnets
########################
Retrieving interna156 (192.168.156.0)

##################
PROCESSING SUBNETS
##################

Processing interna156 (192.168.156.0). 1 networks left.
Done.

 There are, obviously, several hosts up, as you can see:

nmap -sn 192.168.156.0/24

Nmap done: 256 IP addresses (36 hosts up) scanned in 8.58 seconds

Any help would be greatly appreciated.