>>>>>
>>>>>Sorry, I'd forgotten about that behaviour. I guess, if the checkbox and button are at the same level then this would work in the function:

var s = checkbox.id.substr(0, checkbox.id.lastIndexOf("_") + 1) + "btnAgreeContinue"; ;
>>>>>var button = document.getElementById(s);
>>>>>button.disabled = !checkbox.checked;

but there must be something a bit more elegant.....
>>>>
>>>>
>>>>This didn't work either.
>>>
>>>Worked for me with a usercontrol in a form but it does depend on both elements being at the same level. Given that, I don't know why it didn't work for you. But it is ugly anyway.....
>>
>>My two controls are at the same level.
>>
>>>
>>>> I tried my other code to FindControl and pass that in such as this so I could see what the button id was and surprising it is 'btnContinue".
>>>
>>>So, given that the compiler didn't dream that up from scratch where did the name stem from ?
>>>
>>>> So very frustrating to get such a simple thing to work. These things make me want to stick to WPF or Silverlight and avoid ASP.net.
>>>
>>>Very true. Would just have been a simple binding in WPF/Silverlight....
>>>
>>>>

>>>>mmButton thisButton = (mmButton)this.FindControlByName(this, "btnAgreeContinue");
>>>>
>>>>StringBuilder sb = new StringBuilder();
>>>>sb.Append(@"<script language='javascript' type='text/javascript'>");
>>>>sb.Append(@"function SetAgreeAndContinue(checkbox) {");
>>>>sb.Append(@"var button = document.getElementById('" + thisButton.ID + "');");
>>>>sb.Append(@"button.disabled = !checkbox.checked;");
>>>>sb.Append(@"}");
>>>>sb.Append(@"</script>");
>>>>
>>>>string myscript = sb.ToString();
>>>>Page.RegisterStartupScript("S", myscript);
>>>>

>>>
>>>So what does FindControlByName() look like ?
>>
>>That was a method someone posted for me here in VB.net and I converted. It works pretty well and does return this control just fine. Here it is again.
>>

>>public Control FindControlByName<T>(T controlToSearch, string controlID)
>>			where T : System.Web.UI.Control
>>{
>>     Control matchingControl = null;
>>
>>    try
>>    {
>>        foreach (Control subControl in controlToSearch.Controls)
>>        {
>>            if (subControl.ID != null && subControl.ID.EndsWith(controlID))
>>            {
>>	matchingControl = subControl;
>>	break;
>>            }
>>            else
>>            {	
>>	if (matchingControl != null)
>>	    // found it
>>	    break;
>>                     else if (subControl.HasControls())
>>                    {
>>	    matchingControl = this.FindControlByName(subControl, controlID);
>>                    }
>>            }
>>        }
>>    }
>>    catch (Exception e)
>>    {
>>        throw;
>>     }
>>    return matchingControl;
>>}
>>

>
>Thanks for the code.
>But there's no guarantee that the original Id is not duplicated elswhere on the page. So it wouldn't, for example, differentiate between
>'ControlA_Control_B_btnAgreeContinue' and 'ControlA_ControlC_btnAgreeContinue' so you couldn't use the same user control twice on the same form.
>My version would avoid that problem - or it would if it worked :-{
>Did you debug to see where it was going wrong for you ?


I am going to experiment some more with getting the Id using your version. I did get it to work with this, but hard coding the ID is not what I want or need.

protected override void OnInit(EventArgs e)
{
    StringBuilder sb = new StringBuilder();
    sb.Append(@"function SetAgreeAndContinue(checkbox) {");
    sb.Append(@"var button = document.getElementById('ctl00_ctl00_Retirement Mangement System_cphOuterContent_cphMainContent_RightContent_ctrlAgreement_btnAgreeContinue');");
    sb.Append(@"button.disabled = !checkbox.checked;");
    sb.Append(@"}");

    Page.ClientScript.RegisterClientScriptBlock(GetType(), "AgreementScript", sb.ToString(), true);
    base.OnInit(e);
}

At least I know that is the ClientID of the control at runtime, so I will get the clientId of the checkbox to see if it is a match minus the ending. I fear the spaces may be an issue also, so I may track down how this is calculated and make some nameing changes. Like RMS instead of that long name whereever that comes from.
Tim