Can't get mod_rewrite to work on my Ubuntu 14.04 server

Hi. Can anyone please tell me why my htaccess rewrite is not working? I want to remove the .php extensions and I have the following in my .htaccess file, but to no avail. I am running a LAMP stack on Ubuntu 14.04 x64.

Options -indexes

<IfModule mod_rewrite.c> 
RewriteEngine On 
RewriteBase /blog

# Allow any files or directories that exist to be displayed directly 
RewriteCond %{REQUEST_FILENAME} !-f 
RewriteCond %{REQUEST_FILENAME} !-d

# Rewrite all other URLs to index.php/URL 
RewriteRule ^(.*)$ index.php/$1 [L] 
</IfModule>

<IfModule !mod_rewrite.c> 
ErrorDocument 404 index.php 
</IfModule>

<IfModule mod_rewrite.c> 
RewriteEngine On 
RewriteRule	about about.php 
</IfModule>

# Apache Rewrite Rules 
<IfModule mod_rewrite.c> 
Options +FollowSymLinks 
RewriteEngine On 
RewriteBase /

# Add trailing slash to url 
RewriteCond %{REQUEST_FILENAME} !-f 
RewriteCond %{REQUEST_URI} !(\.[a-zA-Z0-9]{1,5}|/|#(.*))$ 
RewriteRule ^(.*)$ $1/ [R=301,L]

# Remove .php-extension from url 
RewriteCond %{REQUEST_FILENAME} !-d 
RewriteCond %{REQUEST_FILENAME}\.php -f 
RewriteRule ^([^\.]+)/$ $1.php

# End of Apache Rewrite Rules 
</IfModule>

Can anyone please take a look and tell me what’s wrong with it? Will be much appreciated.

-Sadman.