keep getting page not found errors after I set mod rewrite

I am trying to get a friendly URL permalink structure set up on my website.

When I change to Month and name for example (site/2011/04/sample-post/) I get:

“If your .htaccess file were writable, we could do this automatically, but it isn’t so these are the mod_rewrite rules you should have in your .htaccess file. Click in the field and press CTRL + a to select all.”
and had this code below that:

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ – [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

So I make the changes to the htaccess file manually and it still does not work. My tech support recommended I try changing <IfModule mod_rewrite.c> to <IfModule mod_rewrite.so> but that did not work either.

Any ideas?
Thanks so much ahead!