The same problem here!
Actually problem starts when we make a symbolic link to our new kernel source directory.
Code:
ln -s /usr/src/linux-2.6.14.2 /usr/src/linux
After doing this, make won't find kernel header files in /usr/src/linux/include/asm directory. So the solution to my problem was:
Code:
ln -s /usr/src/linux-2.6.14.2/include/asm-i386 /usr/src/linux-2.6.14.2/include/asm
And it works now!

Now what i wonder is here: According to this solution the make process uses new source kernel header files( in /usr/src/linux-2.6.14.2/include/asm). Is it the right way or it should use the original kernel header files in /usr/scr/linux-2.6.12/include/asm