I have designed following jqgrid that consists of subgrid but on clicking '+' no call is sent to server.Can someone please guide.

jQuery("#list").jqGrid({
                      caption:" Get Methods",
                   width:"auto",
                      url:'retrieve.action?q=1',
                    datatype: 'json',
                    mtype: 'GET',
                    colNames:['id','name'],
                    loadonce: true,
                    emptyrecords: "No rEcOrDs to view",
                    loadtext: "LoAdInG...",
                    sortable:true,
             colModel:[
                 {name:'id',index:'id', id:'id',editable:false,sorttype:"int"},
                 {name:'name',index:'name', id:'name',editable:true,sortable:true,edittype:"text"}
                 ],
                    pager: jQuery('#pager'),
                    rowNum: 5,
                    rowList: [5, 10, 20, 50],
                    viewrecords: true,
                    sortname:'id',
                    sortorder:'desc',
                    loadonce:false,
                    
                    jsonReader : {
                        root: "array",
                        page: function (obj) { return 1; },
                        total: function (obj) { return 1; },
                        records: function (obj) {
                            return obj.length;
                            },
                        id: "0",
                        userdata: "userdata",
                        repeatitems: false
                        },
                subGrid:true,
                subGridUrl:'retrieve.action?q=2',
                subGridModel:{name:['stationId','structure','facility','description'],
                              width:[80,80,80,80],
                              params:['id'],
                              mapping:['id','standort','beschreibung','lokation']
                }
                
                }).navGrid('#pager',{}, {id:'myedit'});
           }