Avatar Plugin - resides in different directory WPMUforJoomla

Hello, My custom wpmu component for Joomla resides in
below that directory things look normal for wpmu install
The rewrite rule in the install instructions is:
RewriteEngine on
RewriteRule ^(.*/)?avatar/(.*) wp-content/avatar.php?file=$2 [L]

I tried changing it to
RewriteEngine on
RewriteRule ^(.*/)?avatar/(.*) components/com_wpmu/wp-content/avatar.php?file=$2 [L]

When i try to upload the file i get error message
" NOT FOUND The requested URL /administrator/users.php was not found on this server."

Any help getting this plugin to work with my version of wpmu would be greately appreciated...wjwjr