.Htacess Help

[brsy]

I am trying to get my .htaccess working as it should. My current .htaccess looks like the following:

RewriteEngine On
 
RewriteRule ^(|/)$ index.php?url=$1
RewriteRule ^([a-zA-Z0-9_-]+)(|/)$ index.php?url=$1

This code is suppose to turn the index.php?url={value} into /{value}. It works for the most part, but when I try to do the same for my backed, it doesn't work as it should.

RewriteEngine On
 
RewriteRule ^(|/)$ index.php?url=$1
RewriteRule ^([a-zA-Z0-9_-]+)(|/)$ index.php?url=$1
 
RewriteRule ^(|/)$ backend/index.php?url=$1
RewriteRule ^([a-zA-Z0-9_-]+)(|/)$ backend/index.php?url=$1

What's wrong with the .htaccess above?