Your bug is also with:
Setting all binary to suid and sgid is a bad idea, especially since you set their owner to root.chmod -R 6770 /home/amanda/libexec/* /home/amanda/sbin/*
With the owner set to amanda, it's not a good idea either.
You should only set suid and sgid on required binary with correct ownership. run 'make install' as root, it will set all permission correctly. Jean-Louis
