ria services + jquery

i have used ria.js or upshot but same error in jquery: object is undefined

THis error is inside the jquery at 630 lines, inside each:function
--> length = object.length

my javascript can call the domainservice and have the json response, and in the debugger i have this response :

{"GetTodoItemsResult":{"TotalCount":4,"RootResults":[{"IsDone":false,"Title":"Todo item 1","TodoItemId":1},{"IsDone":false,"Title":"Todo item 2","TodoItemId":2},{"IsDone":false,"Title":"Todo item 3","TodoItemId":3},{"IsDone":false,"Title":"Todo item 4","TodoItemId":4}]}}

via Chebli Mohamed