help with loader

i am new with Ext.net please i need help...



<ext:Panel ID="Pnl" runat="server" Region="Center">

<Loader runat="server" Url="mfa.aspx" Mode="Frame" AutoLoad="False">

<LoadMask ShowMask="true" Msg="Loading...<br/>Please Wait..." />

<Params>

<ext:Parameter Mode="Value" Name="WhereCondition" Value="" AutoDataBind="True">

</ext:Parameter>

</Params>

</Loader>

</ext:Panel>

i need to set the value from Javascript but when i make load or reload for the panel the value return to null....



please i am waiting your help