Can't make unit testing works in xamarin studio

I'm trying to follow this tutorials:

www.codeproject.com/Articles/34161/Setup-a-Test-Project-with-NUnit-and-MonoDevelop

but when i click "Run tests", they are gray and no results showed:

how can I make them work ?

Solution

I've found a solution. My windows's firewall was blocking connections, after adding some rules, all started working. That's all +)