ajax is not working in cellselect in jqgrid

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C#

ASP.NET

Ajax

C#4.0

JQGrid

i am using jqgrid in my project there is requirement,when a cell is select in gridview different other fields in webpage will fill so i am using a web method that return a list but problem is that on cellclick,command is not going to aspx.cs page

<script type="text/javascript">
        $(function () {            
            var appsurl = '<%=ConfigurationManager.AppSettings["localpath"].ToString() %>';
            var urlpath = appsurl + 'GetAllLeaveAdjustmentRetirementView';
            "use strict";
            var oItemGrid = $("#UsersGrid");
            oItemGrid.jqGrid({
                url: urlpath,
                mtype: "GET",
                datatype: "json",
                ajaxGridOptions: {
                    contentType: "application/json"
                },
                serializeGridData: function (data) {
                    return JSON.stringify(data);
                },
                colNames: ['','Application No.', 'Date', 'Employee Name', 'Department', 'Designation', 'Date Of Retirement',''],
                colModel: [
                    {
                        name: 'enbl', index: 'enbl', width: 20, align: 'center',
                        formatter: 'checkbox', editoptions: { value: '1:0' },
                        formatoptions: { disabled: false }
                    },
                    { name: 'RetirementProposalNo', index: 'RetirementProposalNo', width: 90 },
                           { name: 'DateOfJoining', index: 'DateOfJoining', width: 90 },
                           { name: 'EmployeeName', index: 'EmployeeName', width: 100 },
                           { name: 'Department', index: 'Department', width: 120 },
                           { name: 'Designation', index: 'Designation', width: 90 },
                           { name: 'DateOfRetirement', index: 'DateOfRetirement', width: 90 },                           
                            { name: 'EmpPorfessionalId', index: 'EmpPorfessionalId', hidden: true }
                ],
                autowidth: true,
                height: 'auto',
                rowNum: 10,
                rowList: [10, 20, 30],
                pager: '#pager1',
                sortname: 'Department',
                loadonce: true,
                viewrecords: true,
                sortorder: "desc",
                rownumbers: true,
                onCellSelect: function (row, col, content, event) {
                    //alert("amit");
                    Id = jQuery("#UsersGrid").jqGrid('getCell', row, 'EmpPorfessionalId');
                    FillDetails(Id);
                    //window.location.href="/KB/answers/HRMS_LeaveAdjustmentAdd.aspx"?id=" + content;
                   
                },

                jsonReader: {
                    root: "d"

                }

            });
            // Edit and display //



            jQuery("#UsersGrid").jqGrid('navGrid', '#pager1', { edit: false, add: false, del: false }, {}, {}, {}, { multipleSearch: true, multipleGroup: true, showQuery: true, closeAfterSearch: true });
        });
        function FillDetails(Id) {
            alert("amit");
            alert(Id);
            debugger;
            $.ajax({
                type: "POST",
                contentType: "application/json; charset=utf-8",
                url: "HRMS_LeaveAdjustmentView.aspx/FillDetails",
                data: '{Id : "' + Id + '" }',
                dataType: "json",
                success: function (data) {
                    $.each(data, function (index, emprs) {
                        $('#ContentPlaceHolder1_lblFinalDecision').val(emprs.FinalDecission);
                        $('#ContentPlaceHolder1_lblChargesHandedFrom').val(emprs.ChargesHandedOverFrom);
                        $('#ContentPlaceHolder1_lblRetirementProposalNo').val(emprs.RetirementProposalNo);
                        $('#ContentPlaceHolder1_lblRetirementProposalDate').val(emprs.RetirementProposalDate);
                        $('#ContentPlaceHolder1_lblRetirementDate').val(emprs.DateofRetirement);
                        $('#ContentPlaceHolder1_lblJobType').val(emprs.JobType);
                        $('#ContentPlaceHolder1_lblDepartment').val(emprs.DepartmentName);
                        $('#ContentPlaceHolder1_lblDesignation').val(emprs.DesignationName);
                        $('#ContentPlaceHolder1_lblAppointmentDate').val(emprs.DateOfAppointment);
                        $('#ContentPlaceHolder1_lblScaleCode').val(emprs.ScaleCode);
                    });

                },
                failure: function (response) {
                    alert(response.d);
                }
            });           
        }
        function OnSuccess(response) {
            alert("done");
        }
    </script>

and my aspx.cs page is like this,i have a web method that return a list

[WebMethod]
        public static List<Details> FillDetails(int Id)
        {
}