Yoast WordPress SEO: XML Sitemapp Plugin

Good day My URL is http:www/paradigmva.co.za I downloaded the Yoast Wordpress SEO and this is the below error it gives me every time I try to access the XML sitemap: HTTP Error 404.0 - Not Found The resource you are looking for has been removed, had its name changed, or is temporarily unavailable. Detailed Error Information Module IIS Web Core Notification MapRequestHandler Handler StaticFile Error Code 0x80070002 Requested URL http://paradigmva.co.za:80/sitemap_index.xml Physical Path F:\Domains\paradigm\paradigmva.co.za\wwwroot\sitemap_index.xml Logon Method Anonymous Logon User Anonymous If you could provide me with step by step instructions on how to correct this error, I would be very grateful. Regards ParadigmVA