Can't Seem to get htaccess rewriting to function

My task is very simply. I want to rewrite http://mysite.org/users/?profile=user to http://mysite.org/users/user

My htaccess file, which is in the root directory of my website, has the following code:

RewriteEngine on
RewriteRule ^users/([a-zA-Z0-9_-]+)$ users/?profile=$1

I have tried many alternatives, checked Stackoverflow and all previous htaccess-related posts on websites, but am stumped at why this would not be functioning at all properly. I simply get a 404 error by going to http://mysite.org/users/user but http://mysite.org/users/profile=user does work. I am stumped.