FilterTemplate + RadCombox, help!

[Tomasz]

Hello.
I have a radgrid with gridtemplate column in it. In gridtemplate column i have placed filtertemplate with radcombox. I'm populating the grid with OnNeedDataSource method. Te code sample looks like this

<telerik:GridTemplateColumn DataField="Obraz" Visible="false" Resizable="false" UniqueName="TemplateColumn"   AllowFiltering="true">
<FilterTemplate>
 <telerik:RadComboBox ID="ComboFilterBox" runat="server" AppendDataBoundItems="true" OnSelectedIndexChanged="FilterCombo_SelectedIndexChanged" DataTextField="Text" DataValueField="Obraz" AutoPostBack="true">
  <items>
  <telerik:RadComboBoxItem Text="Bez filtra" value="1"/>
  <telerik:RadComboBoxItem Text="value1" value="~Gif/pic1.png"/>
  <telerik:RadComboBoxItem Text="value2" value="~/Gif/pic2.png"/>
  <telerik:RadComboBoxItem Text="value3" value="~/Gif/pic3.png"/>
  <telerik:RadComboBoxItem Text="value4" value=""/>
   </items>
   </telerik:RadComboBox>
   </FilterTemplate>
  <ItemTemplate>
  <asp:Image ID="Image1" runat="server" ImageUrl="<%# bind('Obraz') %>" ForeColor="White" />
  </ItemTemplate>
  <HeaderStyle Width="199px" />
   <ItemStyle Width="199px" />
   </telerik:GridTemplateColumn>

and then in server code i have

protected void FilterCombo_SelectedIndexChanged(object o, RadComboBoxSelectedIndexChangedEventArgs e)
        {

            Session["selectedComboitem"] = e.Text;

            string filterExpression;
            if (e.Value != "")
            {
                filterExpression = "([Obraz] = '" + e.Value + "')";
            }
            else
            {
                filterExpression = "";
            }
            RadGrid1.MasterTableView.FilterExpression = filterExpression;
            RadGrid1.MasterTableView.Rebind();
        }

and the filtering is ok, but every time i change the radcombox item after the grid is filtered the combox looks like it is rebinded and it allways show as the selected item is the first item of ComboBox, the filter results are ok, but I realy need to remember the selected item, i have readed many post's and try to filter with client-side (http://www.telerik.com/help/aspnet-ajax/grid-filtertemplate.html) but it does not work for me. Can any one help me please?