If Cron is seemingly not working, then we need to check the logs at /var/log/cron.log. However by default logging in Cron is not enabled.
To enable Cron logs, from a command line enter:
sudo nano /etc/rsyslog.conf
Look for the line:
#cron.* and remove the #
Now restart rsyslog:
sudo /etc/init.d/rsyslog restart
After the next time your Cron job was due to run, you can check the log /var/log/cron.log.