Problem blocking mp3 files

[Raj Nagra]

I'm trying to block mp3 files.  I added the expressionlist line listed below into my 
squidguard.conf.

dest blocked {
  domainlist blocked/domains
  expressionlist blocked/expressions
}

the expressions file contains:
\.(mpv2|mp3)($|\?)

I then did the squid -k reconfigure and the cache.log shows no errors.  domains listed 
in the blocked/domains are blocked like they should be, but mp3 are not being blocked. 
 I'm assuming my expression is wrong, but I don't see the problem. What am I missing?