problem: popup image onclick gridview image using model popup and web service

Like these also i check...
var img = document.getElementById(imgClose)
img.ImageUrl=x.tostring().....is it have some problem in these two line. Thank You.

at
<asp:ScriptManager ID="ScriptManager1" runat="server" enablepagemethods="true" xmlns:asp="#unknown">
it showing these error...
Parser Error Message: Type 'System.Web.UI.ScriptManager' does not have a public property named 'xmlns:asp'.
so i try with this
<asp:ScriptManager ID="ScriptManager1" runat="server" enablepagemethods="true">

but popup image not display... if i do wrong at..
var img = document.getElementById(imgClose)
img.ImageUrl=x.tostring()
Thank you.

My .aspx page Form section like these...
<form id="form1" runat="server">
<div>



<asp:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server" enablepagemethods="true">

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false">
<columns> <asp:BoundField DataField="id" HeaderText="Image ID" />
<asp:TemplateField>
<itemtemplate>
<asp:ImageButton ID="imgBtnTour" runat="server" ImageUrl='<%#DataBinder.Eval(Container.DataItem,"ImagePath") %>' Width="80" OnClientClick="return ShowPopup();"/>




<asp:Button runat="server" ID="btnHiddenPopUp" Style="display: none" />

<asp:ModalPopupExtender ID="mpeTest" runat="server" TargetControlID="btnHiddenPopUp"
PopupControlID="panSaving" BackgroundCssClass="modalBackground" DropShadow="true"
RepositionMode="RepositionOnWindowResize" CancelControlID="imgClose" DynamicServiceMethod="GetDynamicContent" DynamicContextKey='<%# Eval("id") %>' DynamicControlID="imgClose"/>


<asp:Panel runat="server" CssClass="modalPopup" ID="panSaving" Style="display: none">
<table cellpadding="0" cellspacing="0" border="0" width="100%">
<tr>
<td>
<asp:Image ID="imgClose" runat="server" ImageUrl='pics/Koala.jpg' Height="336" Width="430"/>
</td>
</tr>

</table>

</div>
</form>
....
script section like these...
<script src="js/jquery-1.4.2.min.js" type="text/javascript"></script>
<script type="text/javascript">
function ShowPopup() {

//show modal popup window
var modalWindow = '<%= mpeTest.ClientID %>';
$find(modalWindow).show();

//add event handler to hide the modal popup when user click background of the popup window
var backgroundElement = $get(modalWindow + '_backgroundElement');
if (backgroundElement) $addHandler(backgroundElement, 'click', hideModalPopupViaClient);

return false;
}

function hideModalPopupViaClient() {

//hide modal popup window
var modalPopupBehavior = $find('<%= mpeTest.ClientID %>');

if (modalPopupBehavior) {
modalPopupBehavior.hide();
}
}
function Test(contextKey) {
PageMethods.GetDynamicContent(contextKey,
OnSucceeded, OnFailed);
}
function OnSucceeded() {
// Dispaly "thank you."
// write javascript code to bind image path
var img = document.getElementById[imgClose];
img.src = x;

//alert("Thank u")
}
function OnFailed(error) {
// Alert user to the error.
alert(error.get_message());
}

</script>
......

code behind web service part like these....
[System.Web.Services.WebMethod(), System.Web.Script.Services.ScriptMethodAttribute()]
public static string GetDynamicContent(string contextKey)
{
string constr = "connection string";
string query = "SELECT ImagePath FROM imagetable WHERE id = " + contextKey;


SqlDataAdapter da = new SqlDataAdapter(query, constr);
DataTable table = new DataTable();

da.Fill(table);
string x = table.Rows[0]["ImagePath"].ToString();
return x.ToString();

}