binding Model to MVC Telerik Grid throws error (ControllerContext Null Exception)

[HaBo]

I have multiple partialviews rendered on to one view,

each partial view is a strongly typed(different Models) Telerik MVC Grid.

For first two grids those are rendered from partial views has no problem.

but for the third partial view i am rendering is throwing NULL exception.

I have posted my code here.
StackOverFlow

exception:

System.Web.Mvc.ChildActionValueProviderFactory.GetValueProvider(ControllerContext controllerContext)

Controller:

[GridAction]
            public ActionResult CopaySummaryLevel(int PBMID)
            {
                CopayModel cModel = new CopayModel();
                List<CopayModel> _CopayModel = cModel.GetSummaryLevelCopay(PBMID);
                return PartialView("_CopayGridSummaryLevel", new GridModel<CopayModel>
                {
                    Data = _CopayModel
                });
            }

View:

 @model IEnumerable<HRORx.Models.BenefitsFormularyModel>
@using Telerik.Web.Mvc.UI
<h4>
    Summary Level Copay</h4>
@(Html.Telerik().Grid<HRORx.Models.CopayModel>()
            .Name("CopaySummaryLevel")
        .Columns(columns =>
        {
            //columns.Bound(e => e.PharmacyType).Title("Pharmacy Type");
            columns.Bound(e => e.OutOfPocketRangeStart);//.Title("OP Start");
            //columns.Bound(e => e.OutOfPocketRangeEnd).Title("OP End");
            //columns.Bound(e => e.FlatCopayAmount).Title("Flat Fee");
            //columns.Bound(e => e.PercentCopayRate).Title("% Copay");
            //columns.Bound(e => e.MinimumCopay).Title("Min. Copay");
            columns.Bound(e => e.MaximumCopay);//.Title("Max. Copay");//.Format("{0:c}")
        })
    .ClientEvents(events => events.OnRowDataBound("Record_onRowDataBound"))
        .ClientEvents(ev => ev.OnComplete("ShowOrHide"))
                                .DataBinding(dataBinding => dataBinding.Ajax().Select("CopaySummaryLevel", "BenefitsFormulary", new { PBMID = Model.FirstOrDefault().HealthPlanMappingID }))
        .Pageable(paging => paging.PageSize(3))
        .NoRecordsTemplate("No Summary Level Copy Information is available for this Medication.")
        .Sortable()
)

Row bind Event:

function Record_onRowDataBound(e) {
    var grid = $(this).data('tGrid');
}