dhcp reply does not contain requested options

I'm trying to get some dhcp options using the dhcp-inform message. Ethereal
tells me my request and also the reply is well structured. However, asking
for option 6 (name server) or others, the reply always contains options 53,
54 and 1 only. An request e.g. contains in the options section:

option 53: 35 01 08
option 06: 06 04 00 00 00 00
end option: ff

The reply, as written, does not contain option 06.
Any help? Thank!
Martin

Ok, I got it. A DHCP request must contain option 55 listing the desired
option-codes.