Disable AutoSelect in AutoCompleteBox in WP7?

Is there any way to disable the AutoSelect in the AutoCompleteBox in WP7? What happens now is that each time when I write something and it is listed in the search suggestions, the logic runs. This is not what I want, because the user would only like to do the actual search when clicking on a suggestion, the enter key or the search button. So, my question is: How is it possible to disable this?

How it is done now:

In the xaml file, showing the AutoCompleteBox and binds it to key up and selectionchanged:

<toolkit:AutoCompleteBox x:Name="AutoCompleteBox" FilterMode="None" ItemsSource="{Binding SearchSuggestion}" KeyUp="AutoCompleteBoxKeyUp" MinimumPrefixLength="3">
            <i:Interaction.Triggers>
                <i:EventTrigger EventName="KeyUp">
                    <GalaSoft_MvvmLight_Command:EventToCommand Command="{Binding TextBoxKeyUpCommand, Mode=OneWay}" CommandParameter="{Binding Text, ElementName=AutoCompleteBox}"/>
                </i:EventTrigger>
                <i:EventTrigger EventName="SelectionChanged">
                    <GalaSoft_MvvmLight_Command:EventToCommand x:Name="TextBoxSelectionChanged" Command="{Binding TextBoxSelectionChangedCommand, Mode=OneWay}" CommandParameter="{Binding Text, ElementName=AutoCompleteBox}"/>
                </i:EventTrigger>
            </i:Interaction.Triggers>
        </toolkit:AutoCompleteBox>

In xaml.cs I listen to the keyup event and send a message to the viewmodel:

private void AutoCompleteBoxKeyUp(object sender, KeyEventArgs e开发者_运维知识库)
    {
        if (e.Key == Key.Enter)
        {
            Messenger.Default.Send(new ViewModelMessage { Action = ViewModelMessage.ACTION_EXECUTE, Text = AutoCompleteBox.Text });
            Pivot.Focus();
        }
    }

In the ViewModel:

    private void TextBoxKeyUp(string string)
    {
        _string = string;
    }

    private void TextBoxSelectionChanged(string string)
    {
        _string = string;
    }

private void ReceiveMessage(ViewModelMessage message)
    {
        switch (message.Action)
       {
            case ViewModelMessage.ACTION_EXECUTE:
                _string = message.Text;
                break;
        }
    }

The problem seems to be that the SelectionChanged event is raised when I click on the drop down, but also when i type in something that is listed in the drop down. Hope someone can help :)