No new form opens

I'm kinda new in C# so be kind plz.
I'm tring to write an app with Monodevelop so i designed a second form to link it with a button. When a user click it automatically opens the new form (that simply and i can't do it)

Code:

protected void OnAddDatesClicked (object sender, EventArgs e)
    {
            Calendar DatesPanel = new Calendar();
            DatesPanel.Show();       
    }

so what am i missing here?