Accessing JqGrid selected value outside OnSelectRow

i have a Jqgrid with a subgrid. on sub grid i applied the add and delete functionality with asp.net mvc 3. the code is below:

 onSelectRow: function () {
                        var myGrid = $("#" + subgrid_table_id),
                        selRowId = myGrid.jqGrid('getGridParam', 'selrow'),
                        celValue = myGrid.jqGrid('getCell', selRowId, 'PermissionID');
                        permissionID = celValue;
                    }
                });
                $("#" + subgrid_table_id).jqGrid('navGrid', '#' + subgrid_div_id,
            { add: true, del: true, edit: false, search: false },
            { width: '250', url: '@Url.Action("Update", "Role")' },
            { width: '250', url: '/Controler/Action/' + row_id },
            { width: '250', url: "/Controler/Action//" + row_id + "/" + permissionID });

the permissionID is globally defined as 0. but when i pressed De开发者_JAVA技巧lete button of grid its not passing the new value of permissionID to controller. when i debug it its changing the permissionID successfully.

does anyone know whats the issue ?

Thanks

Resolve by a little different scenario, thanks to Oleg . code is below:

$("#" + subgrid_table_id).jqGrid('navGrid', '#' + subgrid_div_id,
    { add: true, del: false, edit: false, search: false },
    { width: '250', url: '/Controler/Action' },
    { width: '250', url: '/Controler/Action/' + row_id })
    .navButtonAdd('#' + subgrid_div_id, {
        caption: '',
        tooltip: 'Delete row',
        buttonicon: "ui-icon-trash",
        onClickButton: function () {
            var myGrid = $("#" + subgrid_table_id);
            var selRowId = myGrid.jqGrid('getGridParam', 'selrow');
            var celValue = myGrid.jqGrid('getCell', selRowId, 'PermissionID');
            if (selRowId === null && celValue === false) {
                alert("Please select row");
                return;
            }
            $.post("/Controler/Action",{"roleid":id1,"id2":selRowId,"id3":celValue},
            function (data) {
                if (data == true) {
                    alert("Association Deleted");
                    $("#" + subgrid_table_id).trigger("reloadGrid");
                }
                else {
                    alert("An error occured");
                }
            });
        },
        position: 'last'
    });