I can see 50 records OK on the grid using the scroll down. But when I arrive to 50 it doesn't continues. Any help?. The code:

  aspx:
 
<igtbl:UltraWebGrid ID="gridNavegar" runat="server" Height="410px"
                            EnableViewState="True" Width="100%"
                            oninitializedatasource="gridNavegar_InitializeDataSource"
                            oninitializelayout="gridNavegar_InitializeLayout">
                            <bands>
                                <igtbl:UltraGridBand>
                                    <addnewrow view="NotSet" visible="NotSet">
                                    </addnewrow>
                                </igtbl:UltraGridBand>
                            </bands>
                            <displaylayout
                            CompactRendering="False" SelectTypeRowDefault="Single"
                                SelectTypeCellDefault="Extended"
                            name="UltraWebGrid1"
                    rowheightdefault="20px" version="4.00">
                                <framestyle height="410px" width="100%">
                                </framestyle>
                                <Pager>
                                </Pager>
                                <activationobject bordercolor="" borderwidth="">
                                </activationobject>
                            </displaylayout>
                        </igtbl:UltraWebGrid>

    C#:
   

    protected void gridNavegar_InitializeLayout(object sender, LayoutEventArgs e)
    {
        gridNavegar.Browser = BrowserLevel.Xml;
        gridNavegar.DisplayLayout.LoadOnDemand = LoadOnDemand.Xml;
        gridNavegar.DisplayLayout.RowsRange = 50;
        gridNavegar.DisplayLayout.XmlLoadOnDemandType = XmlLoadOnDemandType.Synchronous;
    }

    protected void gridNavegar_InitializeDataSource(object sender, UltraGridEventArgs e)
    {       
        gridNavegar.DataSource = (DataTable)Context.Items["dtRes"];    
    }