make-kpkg kernel_headers produces unusable headers

Binary package hint: kernel-package

lsb_release -rd
Description: Ubuntu 9.04
Release: 9.04

kernel-package:
  Installed: 11.015
  Candidate: 11.015
  Version table:
 *** 11.015 0
        500 http://fr.archive.ubuntu.com jaunty/main Packages
        100 /var/lib/dpkg/status

I found this in several earlier fixed bugs, but it seems to happen again with kernel-package 11.015

I need to compile an older kernel version (2.6.24.7) which is the newest for which I can apply the patch i need. here is what i did:
I unpacked the vanilla kernel linux-2.6.24.7, patched to use click (http://read.cs.ucla.edu/click/click-1.7.0rc1.tar.gz) and configured.
Then I make-kpkg --initrd --append-to-version=-click kernel_image kernel_headers

The kernel boots and works properly on this machine, as well on a second machine, where i installed the debs. However, with the kernel-headers installed by the deb package I cannot:
- compile madwifi (make[1]: Entering directory `/usr/src/linux-headers-2.6.24.7-click'
/usr/src/linux-headers-2.6.24.7-click/arch/x86/Makefile:15: /usr/src/linux-headers-2.6.24.7-click/arch/x86/Makefile_32: No such file or directory)
- when I configure click, it does not recognize the kernel as patched. (this seems the to be the check which fails: checking whether netif_tx_lock is declared... no)

Both compiles on the original patched kernel.

I went around the first problem by compiling madwifi on the first machine and creating the deb with make-kpkg modules-image. But there is no deb source for click, so I cannot do it for that too. Anyway, the above is not the expected behavior, right?