MVVM Xamarin Forms Command Binding not working

Hello Everyone,
I am new to this forum, but I encountered a rather annoying problem with Xamarin.Forms.
The thing is I cannot Bind a Command to a button.

I can see that the constructor of my ViewModel runs, however when i press the button, the command never gets executed.

I set the Command property through XAML btw.
But if I set the command property through code behind, then it works. That is quite strange and frustrating.

I get no errors, and when I debug the button, I can see that the Command property is NULL. It is as if I got ignores my binding.

This is the XAML code :
http://pastebin.com/Cj97fatp

This is The ViewModel code :
http://pastebin.com/yuLRdbrN

Thanks in advance