2.6.0-test3 module compilation

[<linuxmodule@altern.org>]

I am trying to compile a module on 2.6.0-test3 kernel. The makefile i am using is a pretty normal one : 

CFLAGS = -D__KERNEL__ -DMODULE -I/usr/src/linux-2.6.0-test3/include -O
dummy.o: dummy.c

The module i am trying to compile is taken from the kernel itself (dummy network device driver). The
compilation works flawlessly but when i try to insert the module i get : invalid module format.
What am i doing wrong because i have modutils and module-init and both work, since the same module (dummy)
compiled with the kernel itself can be inserted and removed without the previous error message.
Is there something i should know about the compilation process ? The kernel-compiled module (dummy.ko) has
about 10 Kbytes and dummy.ko compiled by me has only 2 Kbytes :(

Thank you in advance
Snowdog