Is there something I should know about dhcpd V3 and bootp?

I have a test box running 1.4X/i386 of 2nd May, but 1.4U userland with
bootptest 2.4.1. It can use dhcpclient fine, but bootptest fails.

I have 3 servers:

A:
Internet Software Consortium DHCPD $Name: netbsd-1-3-PATCH001 $
NetBSD 1.3F Sun Jul 12 1998 i386

B:
Internet Software Consortium DHCP Server V2.0b1pl27
NetBSD 1.4U Mon Mar 20 2000 i386

C:
Internet Software Consortium DHCP Server V3.0b2pl0
NetBSD 1.4X Tue May  2 2000 i386

I then try bootptest -h <A,B,C> on the test box.
For all of them /var/log/messages shows correct BOOTREQUEST/BOOTREPLY pairs.
But, bootptest gets "no response" from C.

Any suggestions?

Cheers,

Patrick