I am using Joomla for my site and I have included Expires Headers in my htaccess file, however when checking the site via YSlow the grade is still F, the code in the htaccess file for this is

<IfModule mod_expires.c>
  # Enable expiration control
    ExpiresActive On

  # Default expiration: Immediate after request
    ExpiresDefault "now"

  # CSS and JS expiration: 1 week after request
    ExpiresByType text/css "now plus 1 week"
    ExpiresByType application/javascript "now plus 1 week"
    ExpiresByType application/x-javascript "now plus 1 week"

  # Image files expiration: 1 month after request
    ExpiresByType image/bmp "now plus 1 month"
    ExpiresByType image/gif "now plus 1 month"
    ExpiresByType image/jpeg "now plus 1 month"
    ExpiresByType image/jp2 "now plus 1 month"
    ExpiresByType image/pipeg "now plus 1 month"
    ExpiresByType image/png "now plus 1 month"
    ExpiresByType image/svg+xml "now plus 1 month"
    ExpiresByType image/tiff "now plus 1 month"
    ExpiresByType image/vnd.microsoft.icon "now plus 1 month"
    ExpiresByType image/x-icon "now plus 1 month"
    ExpiresByType image/ico "now plus 1 month"
    ExpiresByType image/icon "now plus 1 month"
    ExpiresByType text/ico "now plus 1 month"
    ExpiresByType application/ico "now plus 1 month"
    ExpiresByType image/vnd.wap.wbmp "now plus 1 month"
    ExpiresByType application/vnd.wap.wbxml "now plus 1 month"
    ExpiresByType application/smil "now plus 1 month"

  # Audio files expiration: 1 month after request
    ExpiresByType audio/basic "now plus 1 month"
    ExpiresByType audio/mid "now plus 1 month"
    ExpiresByType audio/midi "now plus 1 month"
    ExpiresByType audio/mpeg "now plus 1 month"
    ExpiresByType audio/x-aiff "now plus 1 month"
    ExpiresByType audio/x-mpegurl "now plus 1 month"
    ExpiresByType audio/x-pn-realaudio "now plus 1 month"
    ExpiresByType audio/x-wav "now plus 1 month"

  # Movie files expiration: 1 month after request
    ExpiresByType application/x-shockwave-flash "now plus 1 month"
    ExpiresByType x-world/x-vrml "now plus 1 month"
    ExpiresByType video/x-msvideo "now plus 1 month"
    ExpiresByType video/mpeg "now plus 1 month"
    ExpiresByType video/mp4 "now plus 1 month"
    ExpiresByType video/quicktime "now plus 1 month"
    ExpiresByType video/x-la-asf "now plus 1 month"
    ExpiresByType video/x-ms-asf "now plus 1 month"

  # webfonts
    ExpiresByType font/truetype "access plus 1 month"
    ExpiresByType font/opentype "access plus 1 month"
    ExpiresByType application/x-font-woff "access plus 1 month"
    ExpiresByType image/svg+xml "access plus 1 month"
    ExpiresByType application/vnd.ms-fontobject "access plus 1 month"
</IfModule>

Can someone please tell me why it is not being graded by Yslow?

Thanks

GW