Error when Post data to (Update Method) in Rest Service

I am writing Rest Service that Post Data(in Jason format) and  update a table.  This is my Contract:
[OperationContract] [WebInvoke(Method = "POST", ResponseFormat = WebMessageFormat.Json, BodyStyle = WebMessageBodyStyle.Bare, UriTemplate = "UpdateCustomerEmail/{Account_Number}")] void UpdateCustomerEmail(string Account_Number); and my update method is like:

public void UpdateCustomerEmail(string Account_Number) { string Email = "test"; DAL.DataManager dal = new DAL.DataManager(); dal.Update_Customer_Email(Account_Number, Email); }
when I run it like 
http://lo ...