Comment 3 for bug 928007

If I recall correctly, I had this same problem with madwifi on my machines, and it's not a bug in dkms at all, it's cargo-culting a broken dkms.conf (which I did as well). Fixing your dkms.conf like so will make it actually build for the version you requested, rather than the running version:

--- dkms_source_tree/dkms.conf 2012-02-07 02:56:37.000000000 +0000
+++ madwifi-0.9.4/dkms.conf 2010-12-04 22:33:11.000000000 +0000
@@ -43,5 +43,5 @@
 BUILT_MODULE_NAME[13]="ath_rate_onoe"
 BUILT_MODULE_LOCATION[13]="ath_rate/onoe"
 DEST_MODULE_LOCATION[13]="/kernel/drivers/net/wireless"
-MAKE[0]="make modules KERNDIR=/lib/modules/$kernelver"
+MAKE[0]="make modules KERNELPATH=/lib/modules/$kernelver/build"
 AUTOINSTALL="yes"