有如下Visual Basic程序，输入n的值为11。在调试时程序首先出现的错误是.：

Private Sub Command1Click(   )

Dim n As Integer

Dim a(1 To 10) As Integer

n = Val(Text1.Text)

s = 1

For i = 1 To n

s = s * i

a(i) = s

List1.AddItem Str(a(i))

Next i

End Sub

A：

B：

C：

D：