building ALSA against bf2.4

[Robert Kratky <kratky@rob.cz>]

hi,
i need to build alsa against the generic installation bf2.4 kernel 
(2.4.18), but after i installed the 2.4.18 kernel source and did:

:/usr/src/2.4.18# make-kpkg --revision 2.4.18-bf2.4 modules_image

i'm stuck with this result:

---snip---
Starting ALSA sound driver (version 
none):/lib/modules/2.4.18/alsa/snd.o: kernel-module version mismatch
        /lib/modules/2.4.18/alsa/snd.o was compiled for kernel version 
2.4.18
        while this kernel is version 2.4.18-bf2.4.
---snip---

how do i go about this?
robert