Wordpress mod rewrite problem

i have installed wordpress on my site, i have used the built in modrewite, when i post a item, the url is like:
http://www.domain.com/my-item/
the url is works well with the following code:

RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]

and i have add my file to the blog, the file is search.php, and i want turn
http://www.domain.com/search.php?name=search word
to
http://www.domain.com/search_word.html

so i added this line to the .htacess file
RewriteRule ([0-9a-zA-Z_???]*).html /search.php?name=$1
but it will not works, can anyone help me how to write this code?
thanks

 

I tested this and it works.

RewriteEngine On
RewriteBase /
RewriteRule ^([A-Za-z0-9_]*)\.html$ /search.php?name=$1 [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]

Code (markup):

The placement of the custom rewrite rule is important

IF you (temporarily) can change it to

RewriteRule ^([A-Za-z0-9_]*)\.html$ /search.php?name=$1 [R,L]

It will redirect and you can see in the location bar how the url is being rewritten and tweak as needed.

 

thanks so much, it works well. Thanks soooooo much You are BIG helper