Remove query strings

Hi,

I’m testing my page speed at gtmetrix.com and I keep getting an F for “Remove query strings from static resources”. I have unchecked the Browser Cache option for Prevent caching of objects after settings change and also added the following lines to my functions.php file in my theme folder:

function _remove_script_version( $src ){
$parts = explode( ‘?’, $src );
return $parts[0];
}
add_filter( ‘script_loader_src’, ‘_remove_script_version’, 15, 1 );
add_filter( ‘style_loader_src’, ‘_remove_script_version’, 15, 1 );

My site is http://dev.arnpriorhumanesociety.ca

Any other suggestions on how to fix this?

Thanks,
Belinda

http://wordpress.org/extend/plugins/w3-total-cache/