Cache control and expires not working ?

Hi, I can't understand what's overwriting the cache control and expires headers.

Weirdly, the xml files and anything from the subdomain works as expected using the same .htaccess settings.

Apache shows the modules are loaded
mod_expires.c
mod_headers.c


but when i request css and java, images it does not obey htaccess rules that have worked until plesk hosting.

TEST: www.example.com/shop/image.jpg
----------------------------
Connection keep-alive
Date Mon, 16 Dec 2013 16:56:29 GMT
Etag "5285fa0f-92f"
Last-Modified Fri, 15 Nov 2013 10:40:15 GMT
Server nginx

---------------------------
TEST 2 img.example.com/shop/image.jpg

Cache-Control max-age=2592000, public
Connection keep-alive
Date Mon, 16 Dec 2013 16:58:20 GMT
Etag "52860031-92f"
Expires Wed, 15 Jan 2014 16:58:20 GMT
Last-Modified Fri, 15 Nov 2013 11:06:25 GMT
Server nginx
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what can be the cause?