[Openswan Users] I can not make KLIPS install.

[hutx]

I want to build KLIPS kernel module on 2.6.
My linux is Fedoral core 6.
Openswan is openswan-2.6.20rc1

When I run make KERNELSRC=/lib/modules/`uname
-r`/build module minstall, I got an error as below:
make[3]:
/usr/src/kernels/2.6.18-1.2798.fc6-i686/Documentation/DocBook/Makefile:
No such file or directory
make[3]: *** No rule to make target
`/usr/src/kernels/2.6.18-1.2798.fc6-i686/Documentation/DocBook/Makefile'.
 Stop.
make[2]: *** [help] Error 2
+ mkdir -p
/lib/modules/2.6.18-1.2798.fc6/kernel/net/ipsec
+ cp /tmp/openswan-2.6.20rc1/modobj26/ipsec.ko
/lib/modules/2.6.18-1.2798.fc6/kernel/net/ipsec
+ '[' -f /sbin/depmod ']'
+ depmod -a
+ '[' -n net/ipsec ']'
+ mkdir -p
/lib/modules/2.6.18-1.2798.fc6/kernel/net/ipsec
+ '[' -f
/lib/modules/2.6.18-1.2798.fc6/kernel/ipsec.ko -a -f
/lib/modules/2.6.18-1.2798.fc6/kernel/net/ipsec/ipsec.ko
']'
+ set -x
make[1]: Leaving directory `/tmp/openswan-2.6.20rc1'

I check the directory 
/usr/src/kernels/2.6.18-1.2798.fc6-i686/Documentation/DocBook/Makefile.
It does not exist. But I do not know how to install
this direcotory in Kernels.

Please help me. Thanks in advance.