CentOS DHCP server failover won't give out leases

CentOS DHCP server failover won't give out leases

I have followed this tutorial: http://www.madboa.com/geek/dhcp-failover/
However, I can not seem to get a lease at my windows client.
I have set both servers (CentOS 6.2) in virtual machines, connected by the same lan segment. (with VMWare Workstation). My windows Client is also a virtual machine in the same network segment. If I, as in the tutorial, made a single DHCP server, I was able to get a lease. But now that I have 2 dhcp servers, connected with the failover protocol, I can't seem to get the lease.
I have no idea where the problem could be. I have already synced both servers with the ntpdate command, giving them the same time and date (so there is no time difference).
The log from the secondary server gives me 'peer holds all free leases' and the log from the master gives me 'not responding (recovering)'
I can ping from master to slave and slave to master, but I can not ping from the windows client to either the master or the slave. If I do so, I get this:
PING: transmit failed, error 1231.
PING: transmit failed, error 1231.
Please tell me whatever other relevant info I should give.