优化 - 利用浏览器缓存不适用于.js和.png

Question

我正在优化网站，我无法利用.js和.png文件的浏览器缓存。

我的.htaccess看起来像这样：

AddOutputFilterByType DEFLATE text/plain
AddOutputFilterByType DEFLATE text/html
AddOutputFilterByType DEFLATE text/xml
AddOutputFilterByType DEFLATE text/css
AddOutputFilterByType DEFLATE application/xml
AddOutputFilterByType DEFLATE application/xhtml+xml
AddOutputFilterByType DEFLATE application/rss+xml
AddOutputFilterByType DEFLATE application/javascript
AddOutputFilterByType DEFLATE application/x-javascript
AddOutputFilterByType DEFLATE application/vnd.ms-fontobject
AddOutputFilterByType DEFLATE application/x-font
AddOutputFilterByType DEFLATE application/x-font-opentype
AddOutputFilterByType DEFLATE application/x-font-otf
AddOutputFilterByType DEFLATE application/x-font-truetype
AddOutputFilterByType DEFLATE application/x-font-ttf
AddOutputFilterByType DEFLATE font/opentype
AddOutputFilterByType DEFLATE font/otf
AddOutputFilterByType DEFLATE font/ttf


  <ifModule mod_expires>
 ExpiresActive On
 ExpiresDefault "access plus 5 days"
 ExpiresByType image/x-icon "access plus 2592000 seconds"
 ExpiresByType image/jpeg "access plus 2592000 seconds"
 ExpiresByType image/png "access plus 60 days"
 ExpiresByType image/gif "access plus 2592000 seconds"
 ExpiresByType application/x-shockwave-flash "access plus 2592000 seconds"
 ExpiresByType text/css "access plus 604800 seconds"
 ExpiresByType text/javascript "access plus 1 year"
 ExpiresByType text/x-javascript "access plus 1 year"
 ExpiresByType application/javascript "access plus 1 year"
 ExpiresByType application/x-javascript "access plus 1 year"
 ExpiresByType text/html "access plus 600 seconds"
 ExpiresByType application/xhtml+xml "access plus 600 seconds"
 <FilesMatch "\.(bmp|css|flv|gif|ico|jpg|jpeg|js|pdf|png|svg|swf|tif|tiff)$">
        Header set Last-Modified "Mon, 31 Aug 2015 00:00:00 GMT"
    </FilesMatch>
 </ifModule>

缓存似乎与其他文件一起使用，但大多数分析工具都会为png显示错误消息：

或这对于Javascript文件：

我尝试通过.htaccess和各种.htaccess配置添加取消设置最后修改的标头，但似乎没有发生任何事情。我不得不提到我的托管服务提供商正在虚拟机上使用cloudflare。我做错了什么？