Problem compiling modules

[Reiner Klenk]

Greetings,

I have a problem adding kernel modules, e.g., the ov511 module (a webcam 
driver). It is compiled without errors, modprobing results in a lot of 
unresolved symbols, such as:

/lib/modules/2.4.20-8d/kernel/drivers/usb/ov511.o: unresolved symbol 
usb_unlink_urb 

The kernel sources are installed, I have copied the configuration from 
/usr/src/linux-2.4.20-8d/configs/ to /usr/src/linux-2.4.20-8d/.config
then make oldconfig and make dep to configure the sources

The symbols are actually in /boot/System.map, e.g.:

[root@calvados pdq]# grep usb_unlink /boot/System.map
c0175ae4 T usb_unlink_urb
c023158c R __kstrtab_usb_unlink_urb
c027e40c R __ksymtab_usb_unlink_urb

Same problem with the alsa modules.

Any pointers ?

Thanks,
Reiner