Autocomplete with BackgroundWorker does not work - wpf

Question

I'm using AutoCompleteBox from the wpf toolkit and I implement the populating by my own
since there is a lot of data and I want to do the search in a background thread.
this is what heppans when I search for the number 12.
while it should show me 4 results - 12,120,121,122.
What am I doing wrong ?
Guide on msdn that I tried to folow: http://msdn.microsoft.com/en-us/library/system.windows.controls.autocompletebox.populating(VS.95).aspx
XAML:
<Grid>
<Controls:AutoCompleteBox x:Name="txtSearch" Populating="AutoCompleteBox_Populating" Height="30" Background="Beige" />
</Grid>
Code behind:
public partial class Window1 : Window {
private int MAX_NUM_OF_RESULTS = 3;
public List<Person> Persons { get; set; }
public List<string> Results { get; set; }
public Window1() {
InitializeComponent();
Persons = new List<Person>();
for (var i = 0; i < 1000000; i++) {
Persons.Add(new Person { Name = i.ToString() });
}
Results = new List<string>();
}
private void AutoCompleteBox_Populating(object sender, PopulatingEventArgs e) {
e.Cancel = true;
var b = new BackgroundWorker();
b.RunWorkerAsync(txtSearch.SearchText);
b.DoWork += b_DoWork;
b.RunWorkerCompleted += b_RunWorkerCompleted;
}
void b_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) {
txtSearch.ItemsSource = Results;
txtSearch.PopulateComplete();
}
void b_DoWork(object sender, DoWorkEventArgs e) {
Results.Clear();
var counter = 0;
foreach (var person in Persons) {
if (person.Name.StartsWith(e.Argument.ToString())) {
Results.Add(person.Name);
counter++;
if (counter > MAX_NUM_OF_RESULTS) {
break;
}
}
}
}
}
Class Person:
public class Person {
public string Name;
}

Answer 1

Try change the order to the following
var b = new BackgroundWorker();
b.DoWork += b_DoWork;
b.RunWorkerCompleted += b_RunWorkerCompleted;
b.RunWorkerAsync(txtSearch.SearchText);

Answer 2

Are you certain your search logic is actually executing? If so, are the expected results in Results prior to assigning them to ItemsSource?
I think this:
var b = new BackgroundWorker();
b.RunWorkerAsync(txtSearch.SearchText);
b.DoWork += b_DoWork;
b.RunWorkerCompleted += b_RunWorkerCompleted;
Should be this:
var b = new BackgroundWorker();
b.DoWork += b_DoWork;
b.RunWorkerCompleted += b_RunWorkerCompleted;
b.RunWorkerAsync(txtSearch.SearchText);
Otherwise you risk having the worker start before setting up event handlers.