Configuring Apache mod_rewrite

I am trying to configure the mod rewrite module in Gallery2 but as soon as I test it I get the following returned.

Apache mod_rewrite - Testing if mod_rewrite is supported by the server. - Success
Gallery .htaccess file - Testing if Gallery can write to the .htaccess file.
Error - Please create a file in your Gallery directory named .htaccess

touch /home/***/***/*****/gallery2/.htaccess
chmod 666 /home/*****/*****/*****/gallery2/.htaccess

When I do that I then get a 500 Internal server error on all pages and cannot access my gallery2 installation at all.

I have tried every variation of the above synatax I can think of including putting in the physical url and the url as shown through the Drupal mod.

I am using the Drupal 5.1 and have clean urls installed there but had to add an extra / in front of the rewrite rule in the Drupal htaccess file.

I've been searching for the fix for this all day but can't find anything that is answered anywhere that is the same issue.

Any help will be gratefully accepted.
Kind regards
Amanda