'object' does not contain a definition for 'id' why?

[yuanfeng-net]

dynamic viewBag = new DynamicViewBag();

viewBag.Item=new {id=100,name="testItem" };

var model=new PageDetail(){};

RunCompile('

@ViewBag.Item.id

', 'testitemid',
model.GetType(),
model,
(DynamicViewBag)viewBag);

Microsoft.CSharp.RuntimeBinder.RuntimeBinderException:“'object' does not contain a definition for 'id'”

[yuanfeng-net]

Could you tell me how to solve this？