It could be that your sever is PHP4 and not PHP5 and that mod_rewrite is switched off. You need to switch it on. If you have a virtual server then you have no direct access to the server files. You must put commands in your web server that changes the settings so that PHP5 is loaded and mod_rewrite is 'enabled'
First thing to check: Is the server PHP 4 or 5? You need PHP 5.
Create a Get.php file to see what version you are using. Use this code:
<?php
phpinfo();
?>
and call the file getinfo.php
If you see that PHP 5 is already ON the server, then stop reading now. I can't help you!
But...
If the file says PHP 4 then you need a '.htaccess' file which tells it to load PHP 5 (ask your provider for the code). Then try and install again. Here is the code I used, no guarantee it will work for you:
AddType x-mapp-php5 .php
AddHandler x-mapp-php5 .php
If it still doesn't work, then you need to enable mod_rewrite. Ask your provider for the code. From my provider I got this code which I put into the folder where all of my SilverStripe files are. Here is the code my provider gave me (just as an example, it may not work for you):
AddType x-mapp-php5 .php
AddHandler x-mapp-php5 .php
RewriteEngine on
RewriteCond % index/(.*)\.html$
RewriteRule index/(.*)\.html$ /index.php?kategorie=$1
Check the getinfo file again. Check for the command 'allow_url_fopen' in the PHP. This should be 'on' in PHP5. If it is 'off', then you need a php.ini file to switch it on. Put it in the folder where the main SilverStripe folders are.
Then wait a while for the server to update itself. This doesn't happen immediately.
I hope this can help.