my code gota datalist with radio button and iv made it single selectable onitemdatabound....now im trying to evaluate a hiddenfield on basis of selected radio button

my code goes like this

aspx code

<asp:DataList ID="DataList1" runat="server" RepeatColumns = "4"  CssClass="datalist1" 
                RepeatLayout = "Table"  OnItemDataBound="SOMENAMEItemBound"
                CellSpacing="20" onselectedindexchanged="DataList1_SelectedIndexChanged">
                <ItemTemplate>
                <br />
                <table cellpadding = "5px" cellspacing = "0" class="dlTable">
                <tr>
                <td align="center">
                <a href="<%#Eval("FilePath")%>" target="_blank"><asp:Image ID="Image1" runat="server" CssClass="imu" ImageUrl = '<%# Eval("FilePath")%>' 
                Width = "100px" Height = "100px" style ="cursor:pointer" />
                </td>            
                </tr>
                <tr >
                <td align="center">                    
                <asp:RadioButton ID="rdb" runat="server"  OnCheckedChanged="rdb_click" AutoPostBack="True" />            
                <asp:HiddenField ID="HiddenField1" runat="server" Value = '<%#Eval("ID")%>' /> 
                </td>
                </tr>                     
                </table>

 </ItemTemplate> 
</asp:DataList>

code behind

 protected void SOMENAMEItemBound(object sender, DataListItemEventArgs e)
        {
            RadioButton rdb;
            rdb = (RadioButton)e.Item.FindControl("rdb");
            if (rdb != null)
                rdb.Attributes.Add("onclick", "CheckOnes(this);");



        }

  protected void rdb_click(object sender, EventArgs e)
        {
            for (int i = 0; i < DataList1.Items.Count; i++)
            {
                RadioButton rdb;
                rdb = (RadioButton)DataList1.Items[i].FindControl("rdb");
                if (rdb != null)
                {
                    if (rdb.Checked)
                    {
                        HiddenField hf = (HiddenField)DataList1.Items[i].FindControl("HiddenField1");
                        Response.Write(hf.Value);
                    }

                }
            }
        }

the javascript im using...

function CheckOnes(spanChk){


var oItem = spanChk.children;
var theBox= (spanChk.type=="radio") ?
spanChk : spanChk.children.item[0];

xState=theBox.unchecked;
elm=theBox.form.elements;

for(i=0;i<elm.length;i++)
if(elm[i].type=="radio" &&
elm[i].id!=theBox.id)
{
elm[i].checked=xState;
}
}

iam getting an error like this

Microsoft JScript runtime error: Sys.WebForms.PageRequestManagerParserErrorException: The message received from the server could not be parsed. Common causes for this error are when the response is modified by calls to Response.Write(), response filters, HttpModules, or server trace is enabled.
Details: Error parsing near 'pload Demonstration|'.

is there any other way to do this or can nyone plz help to get rid of this problem