title: 'The type or namespace name missing'
body: <p>I followed every step properly to develop an app in xamarin studio as shown in(<a href="https://developer.xamarin.com/guides/android/getting_started/hello,android/hello,android_quickstart/" rel="noreferrer">https://developer.xamarin.com/guides/android/getting_started/hello,android/hello,android_quickstart/</a>)
  But, After building the solution there 11 errors as
  1.'The type or namespace name <strong>Android</strong> could not be found.(Are you missing a using directive or an assembly reference?)' 
  2.'The type or namespace name <strong>Activity</strong> could not be found.(Are you missing a using directive or an assembly reference?)'
  3.'The type or namespace name <strong>Bundle</strong> could not be found.(Are you missing a using directive or an assembly reference?)'
  How to get rid of these errors? Please help</p>
  
  <p>Here's the code---</p>
  
  <pre><code>    using System;
      using Android.App;
      using Android.Content;
      using Android.Runtime;
      using Android.Views;
      using Android.Widget;
      using Android.OS;
  
          namespace PhoneWord
          {
           [Activity (Label = "PhoneWord", MainLauncher = true, Icon ="@drawable/icon")]
    public class MainActivity : Activity
  {
      int count = 1;
  
      protected override void OnCreate (Bundle bundle)
      {
          base.OnCreate (bundle);
  
          // Set our view from the "main" layout resource
          SetContentView (Resource.Layout.Main);
  
  
          // Get our UI controls from the loaded layout:
          EditText phoneNumberText = FindViewById&lt;EditText&gt;(Resource.Id.PhoneNumberText);
          Button translateButton = FindViewById&lt;Button&gt;(Resource.Id.TranslateButton);
          Button callButton = FindViewById&lt;Button&gt;(Resource.Id.CallButton);
          // Disable the "Call" button
          callButton.Enabled = false;
  
          // Add code to translate number
          string translatedNumber = string.Empty;
  
          translateButton.Click += (object sender, EventArgs e) =&gt;
          {
              // Translate user's alphanumeric phone number to numeric
              translatedNumber = Core.PhonewordTranslator.ToNumber(phoneNumberText.Text);
              if (String.IsNullOrWhiteSpace(translatedNumber))
              {
                  callButton.Text = "Call";
                  callButton.Enabled = false;
              }
              else
              {
                  callButton.Text = "Call " + translatedNumber;
                  callButton.Enabled = true;
              }
          };
  
          // Get our button from the layout resource,
          // and attach an event to it
          /*Button button = FindViewById&lt;Button&gt; (Resource.Id.myButton);
  
          button.Click += delegate {
              button.Text = string.Format ("{0} clicks!", count++);
          };*/
      }
    }
  }
  </code></pre>
  
  <p>Thank you</p>