When you make a change to your system file, you have to go through the database update process again, since by default tripwire will not update automatically. Even if you manually do it, you have to copy the database file to its right place. The following code assumes you have tripwire in /usr/local/bin/tw and database file under /var/tripwire. This script helps you update the database easily.
# Run tripwire and update database
/usr/local/bin/tw/tripwire -init -i 2
echo "Moving database over and deleting databases directory"
mv /usr/local/bin/tw/databases/* /var/tripwire/
rm -rf databases