It should work, unless there's some other problem with your configuration.
Here's an example excerpt from a fairly simple SOHO configuration. The "routers" option is in the subnet as this router provides DHCP to multiple NICs:
Code:
option domain-name "example.com";
option domain-name-servers 192.168.1.1;
subnet 192.168.1.0 netmask 255.255.255.0 {
option routers 192.168.1.1;
range 192.168.1.100 192.168.1.200;
}