jQuery Grid Plugin - jqGrid

I can't seem to get the subgrid feature to work. Nothing happens when I click the expand [+] sign. I have put a break inside the  expandSubGridRow function in grid.subgrid.js and see that it does trigger the td element to click. But nothing happens when the click occurs.

$("#MyTable").jqGrid({ 
 datatype: function () {             
 $("#MyTable").jqGrid("addRowData", 1, { Id: 1, Name: "Someone" });          
 },  
 height: 90,         
 colNames: ["#", "Name"],         
 colModel: [ { name: "Id", index: "Id", width: 45, align: "center", sortable: false }, { name: "Name", index: "Name", sortable: false } ], 
 caption: "My Table",         
 subGrid: true,         
 subGridType: function () {             
 alert(1);         
 },         
 subGridUrl: "myurl",         
 subGridModel:   [ { name: ['No','Item','Qty'], width: [55,200,80] } ] 
}); 

myurl never gets called. I've also tried using the subGridRowExpanded option instead of subGridModel, but still not luck. 

Please help. Thanks.

TD