DHCP Problem With PXE

I'm currently working on a little project to get a rescue image loaded through PXE. It shouldn't be that difficult, but personally I don't really work with DHCP (obviously we usually just use static IPs), and DHCP is required for PXE.

I've setup the PXE host server and it's also running DHCPd without errors. This is the configuration of dhcpd.conf:

Code:
ddns-update-style ad-hoc;
option subnet-mask 255.255.255.0;
option domain-name-servers x.x.x.37;

subnet x.x.x.0 netmask 255.255.255.0 {
range x.x.x.155 x.x.x.159;
option broadcast-address x.x.x.255;
option routers x.x.x.1;
next-server x.x.x.153;
filename "pxelinux.0";
max-lease-time 100;
default-lease-time 100;
}
(I have replaced the first three numbers of the IPs with x.x.x for privacy reasons)

That configuration seems fine.. Now the problem is that when I try to get a server to boot with PXE, after a minute or so, it reports that it hasn't received any DHCP offers.

Some side information: both the host and client server are on the same network, but not on the same switch though. I guess that shouldn't matter, or does it?