grml can, why can't my Debian kernel do it?

["Thomas H. George" <lists@tomgeorge.info>]

When I boot from a grml-0.9 cd my dvdrw and cdrw drives are found on hde 
and hdf.  They are mountable and usable.

The grml release info says it is based on Debian and uses a vanilla 
2.6.18-3 kernel with patches and additional modules.

I complied a kernel from Debian linux-source-2.6.18.  On boot up the 
system fails to find the dvdrw and cdrw drives and does not add hde and 
hdf to the list of devices in /dev.  Only entries hda and hdb for the 
two hard drives appear in /dev.

grml can, why can't my Debian kernel do it?

Tom George