Not matching existing files

Hey all, n00b question here. First time user of Hazel.
I have the following rule (the only rule I have):
This rule works when dropping a new file in the folder but NOT on the existing file. I guess Hazel is only triggered when something happens to the folder but why doesn't it detect the old files? There are a ton of PDF files in that folder.
I can see the rule running in every 30 minutes in the log but it doesn't match any of the existing files. When clicking the little eye icon to verify the rule Hazel shows me all the existing files match that rule.
Trying to see if Hazel can help me out before I buy it. Thanks!
I have the following rule (the only rule I have):
if ALL of the following conditions are met for THE FILE OR FOLDER BEING MATCHED
KIND IS PDF
Do the following to the matched file or folder:
RUN SHELL SCRIPT EMBEDDED SCRIPT
This rule works when dropping a new file in the folder but NOT on the existing file. I guess Hazel is only triggered when something happens to the folder but why doesn't it detect the old files? There are a ton of PDF files in that folder.
I can see the rule running in every 30 minutes in the log but it doesn't match any of the existing files. When clicking the little eye icon to verify the rule Hazel shows me all the existing files match that rule.
Trying to see if Hazel can help me out before I buy it. Thanks!