Content Filter Plugin not working

Hello,

I have recently installed OpenFire 3.10.2 and Spark 2.7.2.  I installed the content filter plugin, but can't get it to trigger even with the simple example of "fox,dog". 

Content Filer Settings:

Filter: Enabled

Pattern:  "fox,dog"

On Content Match:  Reject

Rejection Notification:  Disabled

Content Match Notification:  Disabled

As a test I send a colleague a single message of fox (or dog) but nothing happens, the message is sent and received normally. 

Can anyone assist, let me know what can possible be wrong?

Thanks,

Luis