Monitoring a folder for no changes

I have to monitor backups on 22 different servers that use a legacy piece of software. The backup routine fails regularly, and there is no notification system built in to the backup to tell me there is a problem. It's a royal pain.

I am considering Hazel on each of these servers. The idea would be to run once per day, and if there are no changes to the backup folder, email me a notification saying the backups have failed.

I have tried building a rule on my machine:

If ALL of the following conditions are met
Current time is 8:00am any day
Date last modified is not in the last 24 hours
Run shell script

And inside the shell script I have a quick email script to alert me.

It's not working. Any ideas how I might be able to monitor a folder for having no new files and then execute the script?

Is it just files in the folder Hazel is monitoring or does it also include sub-files. For the latter, check out this thread: viewtopic.php?f=4&t=1593#p6500

That one checks if anything has changed but you can modify it to suit your needs.