[Transparant] Snort doesn't work

[Lite-On]

I'm using a pFsense firewall in the datacenter. (transparant firewall)
I think there are some problems with Snort.

The are no items blocked in all the time (+/- 40 days)
Yesterday there where some DDoS attacks on one of the webservers.
The firewall hasn't block any of those attacks.

I have used for more then a year a ClarckConnect firewall + snort. Every day it blocked around 100 attacks.

Snort is enabled (the rules too), but it doesn't do anything?
I'm using Snort performace: "ac-sparsebands", but other options doesn't work too.

Anybody who can help me? :)