Hi,

I have a combobox whose ItemsSource property is bound to an ObservableCollection property and its SelectedIndex property is bound to an integer property respectively.

<ComboBox Name="cmbDealt" ItemsSource="{Binding Path=DealList, Mode=TwoWay}" SelectedIndex="{Binding Mode=TwoWay, Path=DealIndex}"></ComboBox>
<CheckBox IsChecked="{Binding Mode=TwoWay, Path=SomeCondition}" Content="Some Condition"></CheckBox>

My data structure looks like

 private ObservableCollection<string> m_DealList = null;
    private int m_DealIndex = 0;
    private bool m_SomeCondition = false;

    public ObservableCollection<string> DealList
    {
        get
        {
            if (m_DealList == null)
                m_DealList = new ObservableCollection<string>();
            else
                m_DealList.Clear();

            if (m_SomeCondition)
            {
                m_DealList.Add("ABC");
                m_DealList.Add("DEF");
            }
            else
            {
                m_DealList.Add("UVW");
                m_DealList.Add("XYZ");
            }
            return m_DealList;
        }
    }

    public int DealIndex
    {
        get { return m_DealIndex; }
        set
        {
            if (value != -1)
            {
                m_DealIndex = value;
            }
        }
    }

    public bool SomeCondition
    {
        get { return m_SomeCondition; }
        set
        {
            m_SomeCondition = value;
            OnPropertyChanged("DealList");
            OnPropertyChanged("DealIndex");
        }
    }

Now the application loads successfully. However, when the user changes the SelectedIndex of the ComboBox to 1 from 0 and then checks the checkbox (so as to call the "DealIndex" property changed event), the application crashes.

I am not sure why this could be happening. Can someone shed some light and propose a solution?

TIA... Sudeep