i installed pro sites but it want allow me to activate it. i'm recieving a message that there

I'm just trying add this plug in. it says it is installed but it wont let me activate it. what should i do. this is a new blog site and the only other plug in i have in it is "your dashboard plugin" am i missing something?

http://newkingdomofgodonearth.com/blog/wp-admin/plugins.php?error=true&plugin=pro-sites%2Fpro-sites.php&_error_nonce=ac6f763671