请问一个小问题。

[booter]

我用VB写了一个小程序：让一个三色球不停地转动。
程序中我定义了一个开始键：COMMAND1,三个控制不同转速的键：COMMAND2,COMMAND3,COMMAND4。我不能实现COMMAND1的功能：点击小球开始转动。
程序如下：
Dim flag As Integer
Private Sub Command1_Click()
Timer1.Enabled = True
Command1.Visible = False
Command5.Visible = True
End Sub

Private Sub Command2_Click()
Timer1.Interval = 300
End Sub

Private Sub Command3_Click()
Timer1.Interval = 150
End Sub

Private Sub Command4_Click()
Timer1.Interval = 30
End Sub

Private Sub Command5_Click()
Timer1.Interval = 0
End Sub

Private Sub Command6_Click()
Unload Me
End Sub

Private Sub SoundRec1_GotFocus()

End Sub

Private Sub MIDFile1_GotFocus()

End Sub

Private Sub Timer1_Timer()
If (flag - 3) = 0 Then
flag = 0
Else
If flag = 0 Then
Image4.Picture = Image1.Picture
ElseIf flag = 1 Then
Image4.Picture = Image2.Picture
ElseIf flag = 2 Then
Image4.Picture = Image3.Picture
End If
flag = flag + 1
End If
End Sub

[cxjddd]

sp

[rainstormmaster]

Private Sub Timer1_Timer()
select case flag mod 3
case 0
Image4.Picture = Image1.Picture
case 1
Image4.Picture = Image2.Picture
case= 2
Image4.Picture = Image3.Picture
end select
flag = flag + 1
End Sub