Nested for Loop not working for javascript.

function SelectAccess(CheckBox) {

       var chkAc1 = document.getElementById('ctl00_MainContent_CheckBoxAccess').checked;
            if (document.getElementById('ctl00_MainContent_CheckBoxAccess').checked) {

                var ParentGrid = document.getElementById("<%= gvParentGrid.ClientID %>");

                if (ParentGrid.rows.length > 0) {
                    alert(ParentGrid.rows.length);
                    var chidgrid = $('#<%= gvParentGrid.ClientID %> table');

                    var chidgridVal = document.getElementById('ctl00_MainContent_gvParentGrid_ctl02_gvChildGrid');

                    if (chidgridVal.rows.length > 0) {
                        alert(chidgridVal.rows.length);


                        for (var j = 1; j < 11; j++) {

                            for (var i = 1; i <= chidgridVal.rows.length; i++) {

                               document.getElementById('ctl00_MainContent_gvParentGrid_ctl0' + (j + 1).toString() + '_gvChildGrid_ctl0' + (i + 1).toString() + '_ui_access').checked = true;

                               document.getElementById('ctl00_MainContent_gvParentGrid_ctl0' + (j + 2).toString() + '_gvChildGrid_ctl0' + (i + 1).toString() + '_ui_access').checked = true;
                            }
                       }
                    }
                 }
       }

   }