Apache缓存js文件

我已经在windows下配置了Apache以启用这样的缓存

    LoadModule expires_module modules/mod_expires.so
    LoadModule headers_module modules/mod_headers.so
    LoadModule deflate_module modules/mod_deflate.so
ExpiresActive On

ExpiresDefault "access plus 3 days"
ExpiresByType image/x-icon "access plus 1 month"
ExpiresByType image/png "access plus 1 month"
ExpiresByType image/jpg "access plus 1 month"
ExpiresByType image/gif "access plus 1 month"
ExpiresByType image/jpeg "access plus 1 month"
ExpiresByType application/pdf "access plus 1 month"

<IfModule mod_headers.c>
# YEAR
<FilesMatch "'.(ico|gif|jpg|jpeg|png|flv|pdf)$">
  Header set Cache-Control "max-age=29030400"
</FilesMatch>
# WEEK
<FilesMatch "'.(js|css|swf)$">
  Header set Cache-Control "max-age=604800"
</FilesMatch>
# 45 MIN
<FilesMatch "'.(html|htm|txt)$">
  Header set Cache-Control "max-age=2700"
</FilesMatch>
</IfModule>

当我尝试打开js文件直接在浏览器(测试)通过刷新一次又一次，然后每次我得到响应状态200与Firebug。它没有发送状态"304未修改"。你知道我怎样才能做到这一点吗?以下是Firebug头文件的输出。

Response Header
Date        Sat, 13 Aug 2011 01:18:15 GMT
Server      Apache/2.2.19 (Win32) PHP/5.3.6
Last-Modified   Sat, 13 Aug 2011 01:18:15 GMT
Etag        W/"100000000171d-34f08-4aa5f022d9780"
Accept-Ranges   bytes
Content-Length  216840
Cache-Control   max-age=604800
Expires     Tue, 16 Aug 2011 01:18:15 GMT
Keep-Alive      timeout=5, max=100
Connection      Keep-Alive
Content-Type    application/javascript
Request Header
Accept          text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language en-us,en;q=0.5
Accept-Encoding gzip, deflate
Accept-Charset  ISO-8859-1,utf-8;q=0.7,*;q=0.7
Connection          keep-alive
Cookie          PHPSESSID=5k947khv1j27itd7mtp5evtg07
If-Modified-Since   Sat, 13 Aug 2011 01:03:42 GMT
If-None-Match   W/"100000000171d-34f08-4aa5f022d9780"
Cache-Control   max-age=0