Listbox question

I am using code from msdn so that entries in my list box change color based on their index position.  The problem I am having is that the entries do not take on new colors, and it seems that the lbAppointmentDates_DrawItem function never gets called (I put a message box in the code to test this).

Here is my code

this.lbAppointmentDates.DrawItem += new System.Windows.Forms.DrawItemEventHandler(this.lbAppointmentDates_DrawItem);

private void lbAppointmentDates_DrawItem(object sender, System.Windows.Forms.DrawItemEventArgs e)

{

// Set the DrawMode property to draw fixed sized items.

lbAppointmentDates.DrawMode = DrawMode.OwnerDrawFixed;

// Draw the background of the ListBox control for each item.

e.DrawBackground();

// Create a new Brush and initialize to a Black colored brush by default.

Brush myBrush = Brushes.Black;

MessageBox.Show(e.Index.ToString());

// Determine the color of the brush to draw each item based on the index of the item to draw.

switch (e.Index)

{

case 0:

myBrush = Brushes.Red;

break;

case 1:

myBrush = Brushes.Orange;

break;

case 2:

myBrush = Brushes.Purple;

break;

}

// Draw the current item text based on the current Font and the custom brush settings.

e.Graphics.DrawString(lbAppointmentDates.Items[e.Index].ToString(), e.Font, myBrush,e.Bounds,StringFormat.GenericDefault);

// If the ListBox has focus, draw a focus rectangle around the selected item.

e.DrawFocusRectangle();

}

Can anyone tell me why this might not be working?

Thanks,

Paul