System.WebForms.PageRequestManagerParserErrorException The message revieved from the serve

I am trying to use update panel's feature to asyncronously postback and update the data in one of my grid. I am using Master Page and ASPX and a User Control that actually contains the button, Update Panels and a Grid.

When I click btnRefresh I get the following error:

System.WebForms.PageRequestManagerParserErrorException The message revieved from the server could not be parsed...

My ascx looks like this:

<asp:ScriptManagerID="ScriptManager1"runat="server">
</asp:ScriptManager>

<asp:UpdatePanelID="UpdatePanel1"runat="server"UpdateMode="Conditional">
<ContentTemplate>
<asp:ImageButtonID="btnRefresh"runat="server"ImageUrl="~/refresh.gif"OnClick="ImageButton1_Click"/>
</ContentTemplate>
</asp:UpdatePanel>

<asp:UpdatePanelID="UpdatePanel2"runat="server">
<Triggers>
<asp:AsyncPostBackTriggerControlID="btnRefresh"/>
</Triggers>
<ContentTemplate>
<igtbl:UltraWebGridID="UltraWebGrid1"runat="server"Height="200px"Width="468px"style="left: 1px; top: 226px">
</igtbl:UltraWebGrid>
</ContentTemplate>
</asp:UpdatePanel>

Could someone please suggest on this? Is the problem with User Controls??

Guys,

I added the script manager in my Master Page and then added scriptManagerProxy at my user controls which resolved the problem.

Cheers,

Ashish