I shortly had the same problem, while trying to get cryptsetup with luks running under LinuxFromScratch.
bash-3.1# cryptsetup luksOpen /dev/sda1 mt
Command failed: No setup backend available
Finally, it is indeed on option missing in the build-process. the "libdevmapper"
To fix it just compile the cryptsetup-luks again and add the option --enable-libdevmapper to ./configure.
After make, and make install everything is fine..