Dear All,

I have went through the book [Read Word .net c# and Siverlight 15 mvps].
The book was really superb, i have implemented a mvvm pattern and i am trying to consume wcf services in view model usin below code

private readonly ICustomerServiceAgent customerServiceAgent;

private string status;

private ObservableCollection<Customer> customers;

[ImportingConstructor]
public HelloWorldViewModel(ICustomerServiceAgent serviceAgent)
{
this.customerServiceAgent = serviceAgent;
this.LoadCustomersCommand = new DelegateCommand(this.LoadCustomers, this.CanLoadCustomers);
this.status = "Ready";
}
..................
Error:ResolutionfailedException...........
Resolution of the dependency failed type= viewmodel= none.........
ICustomerServiceAgent interface connot be constructed

Please suggest how to solve error and consume wcf service in mvvm sample code.......chapter 7 mvvm framework