Any reason you cannot use a standard asp:RadioButton and use javascript to ensure it is mutually exclusive. I have done this before by adding a custom attribute to the radiobutton and then using a js function to uncheck all items with that attribute and then check the selected one. This works around the IE issue which prevents the groupname attribute from working on radioboxes that are in different containers.

radioButton.InputAttributes.Add("ClientGroupName", "grpRadioList");
radioButton.InputAttributes.Add("onclick",
  string.Format(
     "javascript:radiobuttonToggle( {0} , ClientGroupName , grpRadioList );"  
      ,radioButton.ClientID));

and use the following JS to uncheck all radios and then check the one you want. Note i used InputAttributes instead of Attributes as the radiobutton is wrapped inside a span tag so InputAttributes is for items added to the actual input control rather than the span.

function radiobuttonToggle(selectedRB, attribName, attribValue)
{
    var objRadio = document.getElementById(selectedRB);

    for(i = 0; i < document.forms[0].elements.length; i++)
    {
        elm = document.forms[0].elements[i];
        if (elm.type ==  radio )
        {
            if(elm.getAttribute(attribName) == attribValue)
                elm.checked = false;
        }
    }
    objRadio.checked = true; 
}

You can then expose radioButton.Checked as a property in your CS file and reuse this as a control.

Check Form.Request("radio-name") != null

You only get a non-null value when it s been checked.

Make sure your page elements are being rebuilt correctly on postback. Any binding process that inserted the radio buttons the first time around will have to be re-run before you can access them the second time.

Here is a working example, first I add radios to my webform by the method you linked :

function addRadio()
{
   try{  
        rdo = document.createElement( <input type="radio" name="fldID" /> );  
    }catch(err){  
     rdo = document.createElement( input );  
    }  
    rdo.setAttribute( type , radio );  
    rdo.setAttribute( name , fldID ); 
    document.getElementById( container ).appendChild(rdo);
}

Then at code behind I used only the code below to get the radio s value :

string value = Request["fldID"];

So, be sure you re trying to get the name of the radio buttons at server side. You should use name attribute at server side, not id.