Apache : one of my RewriteRules doesn't working - apache

Question

All of my RewriteRules runs fine except one: ^assets/(.*)$ site/assets/$1 [L]
Actually with this one I get a 404 error but my file is at the good place...
<script type="text/javascript" src="assets/js/script.js" ></script>
File in MAMP/website_name/site/assets/js/script.js
I tried different methods but nothing solve the problem.
The RewriteRule ^js/(.*) site/webroot/js/$1 [L] works well !
Here's my .htaccess
<IfModule mod_rewrite.c>
Options +FollowSymLinks -MultiViews
RewriteEngine On
RewriteBase /
RewriteRule ^assets/(.*)$ site/assets/$1 [L]
RewriteRule fileXupload/server/php/$ fileXupload/server/php/index.php [L]
RewriteRule site/webroot/uploads$ http://signatix.local [R=301,L]
RewriteRule site/webroot/uploads/$ http://signatix.local [R=301,L]
RewriteRule fckeditor/(.*) externallibs/fckeditor/$1 [L]
RewriteRule ^img/(.*) site/webroot/img/$1 [L]
RewriteRule ^imgupload/(.*) site/webroot/imgupload/$1 [L]
RewriteRule ^js/(.*) site/webroot/js/$1 [L]
RewriteRule ^css/(.*) site/webroot/css/$1 [L]
RewriteRule ^upload/(.*) site/webroot/upload/$1 [L]
RewriteRule ^/img/(.*) site/webroot/img/$1 [L]
RewriteRule /upload/(.*) site/webroot/upload/$1 [L]
RewriteRule /upload.php site/upload.php [L]
RewriteRule /md5.php site/md5.php [L]
RewriteRule ^uploads/(.*) site/webroot/uploads/$1 [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^(.*)([[:punct:]]?)(.+)$ index.php?url=$1&%{QUERY_STRING} [L]
#RewriteCond %{HTTP:HTTPS} !on
#RewriteRule (.*) http://%{SERVER_NAME}/$1 [QSA,L,R=301]
</IfModule>
I'm trying to get all of my RewriteRules working.