You need to check whether the event is actually hooked up, or else create a placeholder method that is always called.

You need something like this:

if (SortOrder != null)
   this.SortOrderChanged(this,EventArgs.Empty);

+++ Rick ---


>I know there's alot of code here but.....
>
>I wrote a column header class. When clicked, I want to raise an event. I'm getting the error "Object reference not set to an instance of an object." in the OnSortOrderChanged at the bottom:
>
>

>public enum SortOrder
>{
>    Ascending,
>    Descending,
>    None
>}
>
>public delegate void SortOrderEventHandler(object sender, SortOrderEventArgs e);
>
>public partial class ColumnHeader : UserControl
>{
>    public event SortOrderEventHandler SortOrderChanged;
>
>    private const int SORT_ARROW_TOP = 5;
>    private const int SORT_ARROW_MARGIN = 5;
>    private const int SORT_ARROW_SIZE = 12;
>
>    private SortOrder SortBy = SortOrder.None;
>
>    private string _Caption = "label1";
>    public string Caption
>    {
>        get { return _Caption; }
>        set 
>        { 
>            _Caption = value;
>            lblCaption.Text = _Caption;
>            this.Invalidate();
>        }
>    }
>
>
>    public ColumnHeader()
>    {
>        InitializeComponent();
>    }
>
>
>    private void _ColumnHeader_Paint(object sender, PaintEventArgs e)
>    {
>        // Pens and Brushes
>        Pen penGrey = new Pen(System.Drawing.Color.Gray);
>        Pen penDarkGray = new Pen(System.Drawing.Color.DarkGray);
>        Pen penWhite = new Pen(System.Drawing.Color.White);
>        SolidBrush myBrush = new SolidBrush(Color.DarkGray);
>
>        // Verticle lines on right edge
>        e.Graphics.DrawLine(penGrey, this.Width - 2, 2, this.Width - 2, this.Height - 2);
>        e.Graphics.DrawLine(penWhite, this.Width - 1, 2, this.Width - 1, this.Height - 2);
>
>        // Sort order indicator
>        int iLeft = this.Width - SORT_ARROW_SIZE - 5;
>        Point[] points = new Point[3];
>        switch (SortBy)
>        { 
>            case SortOrder.Ascending:
>                points[0] = new Point(iLeft, SORT_ARROW_TOP);
>                points[1] = new Point(iLeft - 5, SORT_ARROW_SIZE);
>                points[2] = new Point(iLeft + 5, SORT_ARROW_SIZE);
>                break;
>
>            case SortOrder.Descending:
>                points[0] = new Point(iLeft - 5, SORT_ARROW_TOP);
>                points[1] = new Point(iLeft + 5, SORT_ARROW_TOP);
>                points[2] = new Point(iLeft, SORT_ARROW_SIZE);
>                break;
>        }
>
>        if (SortBy != SortOrder.None)
>        {
>            e.Graphics.DrawPolygon(penDarkGray, points);
>            e.Graphics.FillPolygon(myBrush, points);
>        }
>
>        penGrey.Dispose();
>        penDarkGray.Dispose();
>        penWhite.Dispose();
>    }
>    private void _ColumnHeader_Resize(object sender, EventArgs e)
>    {
>        this.Invalidate();
>    }
>    private void _ColumnHeader_Click(object sender, EventArgs e)
>    {
>        _SetSortOrder();
>    }
>
>    private void _SetSortOrder()
>    {
>        switch (SortBy)
>        { 
>            case SortOrder.None:
>                SortBy = SortOrder.Descending;
>                break;
>
>            case SortOrder.Descending:
>                SortBy = SortOrder.Ascending;
>                break;
>
>            case SortOrder.Ascending:
>                SortBy = SortOrder.None;
>                break;
>        }
>        this.Invalidate();
>
>        OnSortOrderChanged(new SortOrderEventArgs(SortBy));
>    }
>
>
>
>    protected virtual void OnSortOrderChanged(SortOrderEventArgs e)
>    {
>        SortOrderChanged(this, e);
>    }
>}
>
>public class SortOrderEventArgs : EventArgs
>{
>    private SortOrder _SortOrder = SortOrder.None;
>    public SortOrder SortOrder
>    {
>        get { return _SortOrder; }
>    }
>    public SortOrderEventArgs(SortOrder NewOrder)
>    { 
>        _SortOrder = NewOrder;
>    }
>
>}
>
>