title: Xamarin: Method does not have correct signature
body: <p>I am trying to create simple multi-screen App.</p>
  
  <p>I added <code>Content Page</code> and <code>button</code> to it. </p>
  
  <p><code>MapPage.xaml.cs</code>:</p>
  
  <pre><code>[XamlCompilation(XamlCompilationOptions.Compile)]
  public partial class MapPage : ContentPage
  {
      public MapPage ()
      {
          InitializeComponent ();
      }
  
      void ShowMap(object s, EventArgs e)
      {
      }
  }
  </code></pre>
  
  <p><code>MapPage.xaml</code>:</p>
  
  <pre><code>&lt;ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
               xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
               xmlns:local="clr-namespace:App14"
               x:Class="App14.MapPage"&gt;
      &lt;ContentPage.Content&gt;
          &lt;StackLayout&gt;
              &lt;Label Text="Welcome to Xamarin Forms!" /&gt;
              &lt;Button Text="show map" 
                      Clicked="ShowMap"/&gt;
          &lt;/StackLayout&gt;
      &lt;/ContentPage.Content&gt;
  &lt;/ContentPage&gt;
  </code></pre>
  
  <p>I am getting error: <code>ShowMap Method does not have correct signature</code></p>
  
  <p>What I am doing wrong?</p>