Restful service post method url using in programming throwing 400 error

See more:

ASP.NET

WCF

REST

Operation method for post method (Expense item is class) :

WebInvoke(Method:="POST", UriTemplate:="CreateExpenseItem", RequestFormat:=WebMessageFormat.Json, ResponseFormat:=WebMessageFormat.Json, BodyStyle:=WebMessageBodyStyle.Bare) _
Function CreateExpenseItem(ByVal objExpense As ExpenseItem) As Integer

Implementation method :

Public Function CreateExpenseItem(ByVal objExpense As ExpenseItem) As Integer Implements IHrmsService.CreateExpenseItem
        Dim Output As Integer
        Output = objEmployee.SaveExpenseDetails _
                                       ( _
                                               objExpense.ExpensemasterID,objExpense.ExpenseID, 
                                               objExpense.Expensename, _
                                               objExpense.ExpenseDate, _
                                               objExpense.Amount, objExpense.Description, _
                                               objExpense.EmpID _
                                       )
      Return Output
 End Function

It is throwing 400 error while using through url in code but Im able to use Get methods :

http://116.145.199.252/ServiceHRMS/HrmsService.svc/web/CreateExpenseItem

Please can anyone help me ..

What Im I doing wrong ?