problem with condition (htaccess)

RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-F
RewriteRule ^([-_!*$@~:.a-zA-Z0-9]+)$ http://url.com/profile.php?username=$1

why this condition not work????

anybody??

What url would you like to have once the rewriterule takes effect? Sounds like something like this http://www.mysite.com/profile

Please let us know.

is for user link profile like:

www.myurl.com/newbie
www.myurl.com/frank

......