title: WPF Binding issue if i call the code from other UC
body: <p>Hi am having a problem to understand binding in WPF.</p>
  
  <p>I have got a User Control and contains ListView, and reading data from database but it takes a minimum of 60 seconds and then fill the listview with data.
  There is a status bar which shows the loading process.</p>
  
  <p>If data is loaded in the memory and User opens the UC, View model loads the data to ListView. Everything works fine.</p>
  
  <p>But if User opens the UC before data read finish and at the end of the reading data i call the same method in the viewModel, in the code behind data is loaded to List item but ListView is still empty. Somehow ListView doesn't show data. </p>
  
  <pre><code> &lt;ListView x:Name="ListViewUK" ItemsSource="{Binding ListOfAccountsFromExchUK}" &gt;
  </code></pre>
  
  <p><strong>View Model</strong></p>
  
  <pre><code>    public class ExchequerViewModel :BaseView
  {
      List&lt;Exch_Account&gt; exch_Accounts_UK;
  
      public ObservableCollection&lt;PAMHeaderModel&gt; ListOfAccountsFromExchUK { get; set; }
  
  
  
      #region CONSTRUCTOR 
      public ExchequerViewModel()
      {
         ListOfAccountsFromExchUK = new ObservableCollection&lt;PAMHeaderModel&gt;();
         PopulateExchequerList();
      }
      #endregion
  
      public void PopulateExchequerList()
      {
          exch_Accounts_UK = ExchequerMemory.ExcAccountList_UK;
          if (exch_Accounts_UK == null)
          {
              AutoClosingMessageBox.Show("Exchequer UK - datas are loading Pleae try again later.", "Information", 2000);
          }
          if (exch_Accounts_UK != null)
          {
              UmbList = new Dictionary&lt;string, string&gt;();
              foreach (var acc in exch_Accounts_UK)
              {
                  ListOfAccountsFromExchUK.Add(new PAMHeaderModel
                  {
                      Company = "UK",
                      RefNo = acc.Code,
                      Name = acc.Company,
                      Subsidiary = acc.UDF6
  
                  });
  
                  UmbList.Add(acc.Code, acc.UDF6); ? acc.UDF6 : "";
              }
              if (ListOfAccountsFromExchUK != null)
                  UKStatusInfoLabel = ListOfAccountsFromExchUK.Count();
          }
  </code></pre>
  
  <p><strong>User Control</strong></p>
  
  <pre><code>    public ExchequerViewModel viewModel;
      public ExchequereUC()
      {
          InitializeComponent();
          viewModel = new ExchequerViewModel();
          DataContext = viewModel;
      }
  </code></pre>