WP Super Cache installation probem

I’m having a minor issue finishing the install of WP Super Cache…0.9.1

When trying to access Plugins within admin backend I get a server 500 error and the line added to PHP error log states missing function admin_url on line 1395 of wp_cache.php ??

WP Super cache tab is functional and displaying correctly.. I haven’t switched caching on as yet because of this problem…

Suggestions please…

Thanks

Status info…
The basic install seems complete…
Files in place.
Rewrite rules added to ht.access ( I’m running Apache under Windows so .htaccess isn’t such a good name ) both in root and subdirectory as suggested.

Rest of site working properly as far as I can tell…