Thought I would work on setting certain UI elements dynamically. Sounded like an easy task until now. Any ideas how to resolve this error?

The ASPX page:

Code:
<%@ Page Language="vb" AutoEventWireup="false" Codebehind="DynamicallyBuildTables.aspx.vb" Inherits="BookChp5a.DynamicallyBuildTables"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
	<HEAD>
		<title>DynamicallyBuildTables</title>
		<meta name="GENERATOR" content="Microsoft Visual Studio .NET 7.1">
		<meta name="CODE_LANGUAGE" content="Visual Basic .NET 7.1">
		<meta name="vs_defaultClientScript" content="JavaScript">
		<meta name="vs_targetSchema" content="http://schemas.microsoft.com/intellisense/ie5">
	</HEAD>
	<body>
		<form id="Form1" method="post" runat="server">
			<P>
				Rows:
				<asp:TextBox id="txtRows" runat="server" />&nbsp; Cols:
				<asp:TextBox id="txtCols" runat="server" /></P>
			<P>
				<asp:CheckBox id="chkBorder" runat="server" Text="Put border around Cells"></asp:CheckBox></P>
			<P>
				<asp:DropDownList id="ddl1" runat="server"></asp:DropDownList>
			</P>
			<P>
				<asp:Button id="cmdCreate" runat="server" Text="Create"></asp:Button><BR>
			</P>
			<P>
				<asp:Table id="Tbl1" runat="server">
					<asp:TableRow ID="row" Runat="server">
						<asp:TableCell id="cell" Runat="server" Text="A Test RowSpan">
							<!-- Instead of using the Text property, you could add other
							     ASP.NET control tags here. --></asp:TableCell>
					</asp:TableRow>
				</asp:Table>
			</P>
		</form>
	</body>
</HTML>
The code behind file:

VB Code:
  1. Public Class DynamicallyBuildTables

  2.     Inherits System.Web.UI.Page

  3.     ' Inherits System.Web.UI.WebControls

  4. #Region " Web Form Designer Generated Code "

  5.  
  6.     'This call is required by the Web Form Designer.

  7.     <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()

  8.  
  9.     End Sub

  10.     Protected WithEvents txtRows As System.Web.UI.WebControls.TextBox

  11.     Protected WithEvents txtCols As System.Web.UI.WebControls.TextBox

  12.     Protected WithEvents chkBorder As System.Web.UI.WebControls.CheckBox

  13.     Protected WithEvents cmdCreate As System.Web.UI.WebControls.Button

  14.     Protected WithEvents Tbl1 As System.Web.UI.WebControls.Table

  15.     Protected WithEvents ddl1 As System.Web.UI.WebControls.DropDownList

  16.  
  17.     'NOTE: The following placeholder declaration is required by the Web Form Designer.

  18.     'Do not delete or move it.

  19.     Private designerPlaceholderDeclaration As System.Object

  20.  
  21.     Private Sub Page_Init(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Init

  22.         'CODEGEN: This method call is required by the Web Form Designer

  23.         'Do not modify it using the code editor.

  24.         InitializeComponent()

  25.     End Sub

  26.  
  27. #End Region

  28.  
  29.     Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

  30.         'Put user code to initialize the page here

  31.         If IsPostBack = False Then

  32.             Tbl1.Visible = False

  33.             ddl1.Items.Add("Dashed")

  34.             ddl1.Items.Add("Dotted")

  35.             ddl1.Items.Add("Doubled")

  36.             ddl1.Items.Add("Groove")

  37.             ddl1.Items.Add("Inset")

  38.             ddl1.Items.Add("None")

  39.             ddl1.Items.Add("NotSet")

  40.             ddl1.Items.Add("Outset")

  41.             ddl1.Items.Add("Ridge")

  42.             ddl1.Items.Add("Solid")

  43.         Else

  44.             Tbl1.Visible = True

  45.         End If

  46.         '        Tbl1.BorderStyle = BorderStyle.Inset

  47.         Tbl1.BorderWidth = Unit.Pixel(1)

  48.     End Sub

  49.  
  50.     Private Sub cmdCreate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdCreate.Click

  51.         'Remove all current rows and cells.

  52.         'This would not be necessary if you set

  53.         'EnableViewState = False.

  54.         Tbl1.Controls.Clear()

  55.         Dim strRows As String = txtRows.Text

  56.         Dim strCols As String = txtCols.Text

  57.         Dim strBorder As String = "BorderStyle." & ddl1.SelectedItem.Text

  58.         Dim i, j As Integer

  59.         For i = 1 To Val(strRows)

  60.             'Create a new tablerow object.

  61.             Dim rowNew As New TableRow

  62.             'put the new tablerow into the table object.

  63.             Tbl1.Controls.Add(rowNew)

  64.             For j = 1 To Val(strCols)

  65.                 'Create a new TableCell object.

  66.                 Dim cellNew As New TableCell

  67.                 '***************************** standard text

  68.                 'cellNew.Text = "Example Cell (" & i.ToString() & ","

  69.                 'cellNew.Text &= j.ToString() & ")<br />"

  70.                 '*****************************

  71.                 '***************************** Added as objects

  72.                 Dim lblNew As New Label

  73.                 Dim imgNew As New System.Web.UI.WebControls.Image

  74.                 imgNew.ImageUrl = "/images/smile.gif"

  75.                 lblNew.Text = "hello"

  76.                 cellNew.Controls.Add(lblNew)

  77.                 cellNew.Controls.Add(imgNew)

  78.                 '*****************************

  79.  
  80.                 If chkBorder.Checked Then

  81.                     ' Not working accurately, but dows show how to 

  82.                     ' dynamically set border style.

  83.                     txtCols.Text = strBorder

  84.                     cellNew.BorderStyle = strBorder 'Bombs right here

  85.                     cellNew.BorderWidth = Unit.Pixel(4)

  86.                 End If

  87.                 'Put the TableCell in the TableRow.

  88.                 rowNew.Controls.Add(cellNew)

  89.             Next

  90.         Next

  91.     End Sub

  92. End Class

Also, Is there a way to populate the ddl1.items.add("") list within the code and not hard coding?