How to set default Selected Item in AJAX CascadingDropDown DropDownList in ASP.Net

hi

I used below code to set default value for DDL

state.Items[1].Selected = true;

now I use cascading for DDL how I can same thing for cascading?

 <cc1:CascadingDropDown ID="CDLdistrict" TargetControlID="DDLDO" PromptText="All"
                                                            PromptValue="" ServicePath="../ServiceCS.asmx" ServiceMethod="GetDistrict" runat="server"
                                                            Category="District" ParentControlID="DDLzoneO" />

Best Regards

Neda