VB MsgBox vbYesNo没有声明

Question

我有简单的部分程序麻烦错误：VB MsgBox是没有声明。

如果它很重要，我正在使用Visual Studio Express 2012和Windows 7。

VbYesNo is not declared. It may be inaccessible due to its protection level.

很多感谢的麻烦在过去没有发生过。

哪些程序麻烦：

userchoice = MsgBox("Did you mean to enter A?", vbYesNno, "Yes") ' if yes add, if no subtract 

所有程序：

Public Class MainForm 
Public stroperation, strnumber1, strnumber2, strresult As String 
Public decnumber1, decnumber2, decresult As Decimal 
Public operation, userchoice 
Private Sub calculateButton_Click(sender As Object, e As EventArgs) Handles calculateButton.Click 
    operation = operationTextBox.Text 
    stroperation = CStr(operation) 
    strnumber1 = number1TextBox.Text 
    decnumber1 = CDec(strnumber1) 
    strnumber2 = number2TextBox.Text 
    decnumber2 = CDec(strnumber2) 
    If stroperation = "S" Or stroperation = "s" Then 
     decresult = decnumber1 - decnumber2 
     strresult = CStr(decresult) 
     resultLabel.Text = "Difference: " & strresult 
    ElseIf stroperation = "A" Or stroperation = "a" Then 
     decresult = decnumber1 + decnumber2 
     strresult = CStr(decresult) 
     resultLabel.Text = "Sum: " & strresult 
    Else 
     userchoice = MsgBox("Did you mean to enter A?", vbYesNno, "Yes") ' if yes add, if no subtract 
     If userchoice = vbYes Then 
      decresult = decnumber1 + decnumber2 
      strresult = CStr(decresult) 
      resultLabel.Text = "Sum: " & strresult 
     ElseIf userchoice = vbNo Then 
      decresult = decnumber1 - decnumber2 
      strresult = CStr(decresult) 
      resultLabel.Text = "Difference: " & strresult 
     End If 
    End If 
End Sub 

Private Sub MainForm_Load(sender As Object, e As EventArgs) Handles MyBase.Load 

End Sub 
End Class 

Answer 1

你有一个错字：

userchoice = MsgBox("Did you mean to enter A?", vbYesNno, "Yes") 

公告的 “NN”。它应该是vbYesNo