nagios check_dhcp

I installed check_dhcp.c so that nagios will check
dhcp server.

I run cc check_dhcp.c this produce a.out(Executable
and Linking Format (ELF) files)

when I run ./a.out

I get the following in /var/log/messages

dhcpd: DHCPDISCOVER from 00:30:40:52:46:fc via eth0
dhcpd: DHCPOFFER on 161.67.140.172 to
00:30:40:52:46:fc via eth0

../a.out attually make a dhcp request and according to
the /var/log/messages
a dhcpoffer was made but ./a.out returns the following
DHCP problem: No DHCPOFFERs were received.

My client machine where ./a.out was been excuted form
has it mac address in my dhcpd.conf on my dhcp server.

what am I doing wrough? can you help please?