I installed and tried to network activate this plugin

Hi, I installed and tried to network activate this plugin (simple sitemap for multisites) and I get the following error...
"Simple Sitemaps file "sitemap.php" not found. Please move it to /wp-content/ before activating."

I looked and the sitemap.php file is one of the plugin files and it appears to already be in the right location? I also deactivated all plugins to rule out any compatability issues and I get the same error.