Trying to install Pro Sites on Windows Azure, I got this

Trying to install Pro Sites on Windows Azure, I got this message: Fatal error: Call to undefined function switch_to_blog() in C:\DWASFiles\Sites\solvr\VirtualDirectory0\site\wwwroot\wp-content\plugins\pro-sites\pro-sites.php on line 194

What's wrong here, or does Pro Sites not work on Windows?