Did you update the symlinks for kernel and modules version? IF you didn't, run
Code:
ln -s /usr/src/linux-2.6.11 /usr/src/linux
ln -s /usr/src/linux-2.6.11 /lib/modules/2.6.11/build
Then go to the directory where you unpacked the driver sources run "make distclean" and re-run make.