custom permalink problem

[amigo1]

when i am setting permalinks at /%postname%/,, the post is giving 404 error ..
where as if i change it to other than custom structure,it loads fine..here is 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

i can not figure out the problem..http://headwaythemes.com/members/sup...lies/frown.gif...can anyone plz help me..if its wrong place to post this,,plz forgive me

[amigo1]

uh sorry for irrelevent link there,,there is no edit button to delete that.
i have already contacted the support regarding my problem,,bad day