Question

I am using the default .htaccess file of opencart below, I manually added the last 2 lines.

RewriteBase /
RewriteRule ^sitemap.xml$ index.php?route=feed/google_sitemap [L]
RewriteRule ^googlebase.xml$ index.php?route=feed/google_base [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_URI} !.*\.(ico|gif|jpg|jpeg|png|js|css)
RewriteRule ^([^?]*) index.php?_route_=$1 [L,QSA]

RewriteCond %{REQUEST_URI} diger_olcu_aletleri
RewriteRule ^diger_olcu_aletleri$ http://www.hirdavatdeposu.com/diger-olcu-aletleri

I have checked using the website (http://htaccess.madewithlove.be/) and it changes my url

diger_olcu_aletleri

to

diger-olcu-aletleri

as expected, however it does not work in my website. What can be the problem ?

Below is my complete .htaccess file.

# 1.To use URL Alias you need to be running apache with mod_rewrite enabled. 

# 2. In your opencart directory rename htaccess.txt to .htaccess.

# For any support issues please visit: http://www.opencart.com

Options +FollowSymlinks

# Prevent Directoy listing 
Options -Indexes

# Prevent Direct Access to files
<FilesMatch "\.(tpl|ini|log)">
 Order deny,allow
 Deny from all
</FilesMatch>

# SEO URL Settings
RewriteEngine On
# If your opencart installation does not run on the main web folder make sure you folder it does run in ie. / becomes /shop/ 

RewriteBase /
RewriteRule ^sitemap.xml$ index.php?route=feed/google_sitemap [L]
RewriteRule ^googlebase.xml$ index.php?route=feed/google_base [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_URI} !.*\.(ico|gif|jpg|jpeg|png|js|css)
RewriteRule ^([^?]*) index.php?_route_=$1 [L,QSA]

RewriteCond %{REQUEST_URI} diger_olcu_aletleri
RewriteRule ^diger_olcu_aletleri$ http://www.hirdavatdeposu.com/diger-olcu-aletleri

### Additional Settings that may need to be enabled for some servers 
### Uncomment the commands by removing the # sign in front of it.
### If you get an "Internal Server Error 500" after enabling any of the following settings, restore the # as this means your host doesn't allow that.

# 1. If your cart only allows you to add one item at a time, it is possible register_globals is on. This may work to disable it:
# php_flag register_globals off

# 2. If your cart has magic quotes enabled, This may work to disable it:
# php_flag magic_quotes_gpc Off

# 3. Set max upload file size. Most hosts will limit this and not allow it to be overridden but you can try
# php_value upload_max_filesize 999M

# 4. set max post size. uncomment this line if you have a lot of product options or are getting errors where forms are not saving all fields
# php_value post_max_size 999M

# 5. set max time script can take. uncomment this line if you have a lot of product options or are getting errors where forms are not saving all fields
# php_value max_execution_time 200

# 6. set max time for input to be recieved. Uncomment this line if you have a lot of product options or are getting errors where forms are not saving all fields
# php_value max_input_time 200

Answer 1

The last line of the OpenCart .htaccess rules basically catches anything and then stops. Try your two lines just after the RewriteBase line as that should work. The .htaccess file is checked line by line and the L in [L,QSA] on the last OC line means to stop after that line is run