ASP.NET VB.NET Why is control undefined?

When screen is displayed using ASP.NET, IE6 provides error message:
     Line 14
     Char 9
     Error: 'CheckBox1' is undefined
     Code: 0
     URL: http://localhost/atlins2/controls/toy.aspx

VB.NET source Code
-----------------------
<%@ Page Language="VB" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Untitled Page</title>
    <script language="javascript">
        CheckBox1.onClick = CheckBox1_Changed;
       
        function CheckBox1_Changed() {
            alert("CheckBox1 Changed")
        }
    </script>
</head>
<body>
    <form id="form1" runat="server">
        <asp:CheckBox ID="CheckBox1" runat="server" Text="CheckBox1" />
    </form>
</body>
</html>

Code as seen by Internet Explorer 6
--------------------------------------------
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head><title>
      Untitled Page
</title>
<script language='javascript' src='http://127.0.0.1:1026/js.cgi?caw&r=16944'></script>
<script language="javascript">
        CheckBox1.onClick = CheckBox1_Changed;               /* Tried this */
        function window.onload() {                                      /* and tried this too */
            CheckBox1.onClick = CheckBox1_Changed;
        }

        function CheckBox1_Changed() {
            alert("CheckBox1 Changed")
        }
    </script>
</head>
<body>
    <form name="form1" method="post" action="toy.aspx" id="form1">
<div>
<input type="hidden" name="__VIEWSTATE" id="__VIEWSTATE" value="/wEPDwULLTE3MzUzNTIzMDhkGAEFHl9fQ29udHJvbHNSZXF1aXJlUG9zdEJhY2tLZXlfXxYBBQlDaGVja0JveDGuIpQWwMDERj7uUtS6dBud+lEwrw==" />
</div>
        <input id="CheckBox1" type="checkbox" name="CheckBox1" /><label for="CheckBox1">CheckBox1</label>
<div>

<input type="hidden" name="__EVENTVALIDATION" id="__EVENTVALIDATION" value="/wEWAgLZg5nTBAKC5Ne7CUdNgqqnpnm1Xeak0Aqo72nkX74K" />
</div></form>
</body>
</html>
--------------------------

What needs to change so that the event callback for checkbox can work?
brotherbill999Asked:
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PAQ_ManConnect With a Mentor Commented:
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PAQ_Man
Community Support Moderator
0
 
gops1Commented:
Why this way: CheckBox1.onClick

May be it should be like this:

document.form1.CheckBox1.onClick
0
 
brotherbill999Author Commented:
Hi gops1,
  Tried that, but it didn't work.  Keep trying.  Better yet, build a toy, get it working, and then you'll *know* you have a solution.
Brother Bill

<%@ Page Language="VB" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Untitled Page</title>
    <script language="javascript">
        function window.onload() {
            document.form1.CheckBox1.onClick = CheckBox1_Changed;           /* Changed it according to your tip.  Didn't help */
        }
        function CheckBox1_Changed() {
            alert("CheckBox1 Changed")
        }
    </script>
</head>
<body>
    <form id="form1" runat="server">
        <asp:CheckBox ID="CheckBox1" runat="server" Text="CheckBox1" />
    </form>
</body>
</html>
0
 
brotherbill999Author Commented:
Here is what does work.
1. add onload function with parenthesis to <body onload= ... >
2. for convenience, define a variable for CheckBox1 = document.form1.CheckBox1
3. when using onclick event, use all lowercase.

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Untitled Page</title>
    <script language="javascript">
        var CheckBox1;
        function load() {
            alert("load");
            CheckBox1 = document.form1.CheckBox1
            CheckBox1.onclick = CheckBox1_Changed;
        }
        function CheckBox1_Changed() {
            alert("CheckBox1 Changed")
        }
    </script>
</head>
<body onload=load()>
    <form id="form1" runat="server">
        <asp:CheckBox ID="CheckBox1" runat="server" Text="CheckBox1" />
    </form>
</body>
</html>
0
 
brotherbill999Author Commented:
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