mod_expires help

Hello:

I have mod_expires installed on Ubuntu 14.04 Apache 2.4.7.

I have some very case specific expire requirements, so I am stetting these using .htaccess on folder by folder basis as needed, and they seem to be working fine for the main default configuration for the server.

I also have some sub-domains as virtual servers on the same server, however mod_expires does not seem to be working on the sub-domains.

I am sure I am missing something simple, but not sure what.

I tried re-enabling mod_expires, and restarting apache, but still no luck.

Any help would be appreciated.

Thanks!