Q:

C# Updating a dropdown box with value from another dropdown box

I have a dropdown box that lists authors names:
I need to have this box update with the selected value from a 2nd dropdown list.
This clears the values from the authors dropdown list but it does not update the box with the selected value from the 2nd dropdown list.  What do I need to include to get the value of the lbAuthorList to display the selected value from DroopDownList1?
protected void update_SelectedItem(object sender, EventArgs e)
{
    lbAuthorList.Items.Clear();
    lbAuthorList.Text = DropDownList1.SelectedItem.Text;

}

  <asp:DropDownList runat="server" ID="lbAuthors" style="float:left;" 
    DataSourceID="odsAuthorList" DataTextField="DisplayAuthorName" DataValueField="AuthorID" 
    onselectedindexchanged="lbUserList_SelectedIndexChanged" 
    AppendDataBoundItems="True" >
      </asp:DropDownList>
  <asp:DropDownList ID="DropDownList1" runat="server" AppendDataBoundItems="True" 
    DataSourceID="SqlDataSource2" DataTextField="Display_AuthorName"  EnableViewState="false"
    DataValueField="Display_AuthorName" OnSelectedIndexChanged="update_SelectedItem" AutoPostBack="true">
</asp:DropDownList>

A:

You need to add new item to drop down list, 
protected void update_SelectedItem(object sender, EventArgs e)
{
    lbAuthorList.Items.Clear();
    lbAuthorList.Items.Add(new ListItem(DropDownList1.SelectedItem.Text, DropDownList1.SelectedItem.Text));
    lbAuthorList.Items.FindByValue(DropDownList1.SelectedItem.Text).Selected = true;
}

