金山区团区委书记:VB计算器差错

下面是我刚写的一个计算器，好像除了加法都错了？？我觉得是if那个语句的逻辑错误，怎么修正一下呢？谢谢
(是不是因为我的逻辑思维不好啊？？)

Option Explicit
Dim x(4) As Double

Private Sub Command1_Click()
Text1.Text = Val(Val(Text1.Text) & Val(1))
End Sub

Private Sub Command10_Click()
Text1.Text = Val(Val(Text1.Text) & Val(0))
End Sub

Private Sub Command11_Click()
x(1) = Val(Text1.Text)
Text1.Text = Val(0)
End Sub

Private Sub Command12_Click()
x(2) = Val(Text1.Text)
Text1.Text = Val(0)
End Sub

Private Sub Command13_Click()
x(3) = Val(Text1.Text)
Text1.Text = Val(0)
End Sub

Private Sub Command14_Click()
x(4) = Val(Text1.Text)
Text1.Text = Val(0)
End Sub

Private Sub Command15_Click()
x(0) = Val(Text1.Text)
If Val(x(1)) <> Val(0) Then
Text1.Text = Val(Val(x(1)) + Val(x(0)))
ElseIf Val(x(2)) <> Val(0) Then
Text1.Text = Val(Val(x(2)) - Val(x(0)))
ElseIf Val(x(3)) <> Val(0) Then
Text1.Text = Val(Val(3) * Val(0))
ElseIf Val(x(4)) <> Val(0) Then
Text1.Text = Val(Val(4) / Val(0))
End If
End Sub

Private Sub Command16_Click()
Text1.Text = Val(0)
End Sub

Private Sub Command2_Click()
Text1.Text = Val(Val(Text1.Text) & Val(2))
End Sub

Private Sub Command3_Click()
Text1.Text = Val(Val(Text1.Text) & Val(3))
End Sub

Private Sub Command4_Click()
Text1.Text = Val(Val(Text1.Text) & Val(4))
End Sub

Private Sub Command5_Click()
Text1.Text = Val(Val(Text1.Text) & Val(5))
End Sub

Private Sub Command6_Click()
Text1.Text = Val(Val(Text1.Text) & Val(6))
End Sub

Private Sub Command7_Click()
Text1.Text = Val(Val(Text1.Text) & Val(7))
End Sub

Private Sub Command8_Click()
Text1.Text = Val(Val(Text1.Text) & Val(8))
End Sub

Private Sub Command9_Click()
Text1.Text = Val(Val(Text1.Text) & Val(9))
End Sub

Private Sub Text1_Change()
If Len(Text1.Text) > 20 Then
Text1.Text = Val(0)
MsgBox "溢出！原因：数据过大！", , "温馨提示--左兴东"
End If
End Sub