or
<ajax:RadComboBox ID="DdlPoCat" runat="server" Width="280px" EnableLoadOnDemand="True" EnableVirtualScrolling="true" EnableAutomaticLoadOnDemand="true" > <ItemTemplate> <asp:CheckBox runat="server" ID="chkPoCat" Text='<%#Eval("ParamDesc")%>'/> </ItemTemplate> </ajax:RadComboBox>dsPOCategory = getAppParam("PO_CAT") DdlPoCat.DataSource = dsPOCategory DdlPoCat.DataTextField = "ParamDesc" DdlPoCat.DataValueField = "ParamId" DdlPoCat.DataBind()