Cant update permalinks!

Hi friend,
I run wordpress 3.3.1,I’m using mantra theme by cryout creations.Now i come to my problem.
I cant update my permalinks. When i select default it works perfectly.But whenever i change it into other options it doesn’t works even it updates the .htaccess file.
Whenever i try to access my post with newly updated permalinks it gives me “Nothing Found The requested URL /2012/04/this-is-a-test/ was not found on this server.” Acutally its a 404 error.
First i manually changed my .htaccess file as per the wordpress code.It didnt work.Then i changed it into “chmod 666 .htaccess” so that the wordpress can save by itself.It did,but no use at all.
I can only use the default option.But not any other.Please help me with this.I suppose that the problem is with my MySQL database.
This is the code in my .htaccess file:
`# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ – [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

# END WordPress`

Please visit my site http://balakrish.zapto.org so that you can figure out the problem. [my site may be shutdown when you open it,the reason is we face load shedding problems]
Thank you.