B语言的问题

代码如此，我做了个进度条，可是我想进度条到100%就执行MsgBox显示文字（"通知"为标题，"成功"为内容）

或者在20%、50%任意一个小于100%的时候就显示MsgBox文字，应该怎样搞呢？

Private Sub Form_Load()
Picture1.ForeColor = vbBlue
Picture1.FontBold = True
Picture1.AutoRedraw = True

End Sub

Private Sub Command100_Click()
Dim i As Long, j As Long
For i = 1 To 20
For j = 1 To 100000
DoEvents
Next
Call Progress(i * 5)

Next
End Sub

Private Sub Progress(percent As Long)
Dim msg As String
msg = percent & "%"
With Picture1
.Cls
Picture1.Line (0, 0)-(percent / 100 * .ScaleWidth, .ScaleHeight), vbGreen, BF
.CurrentX = (.ScaleWidth - .TextWidth(msg)) / 2
.CurrentY = (.ScaleHeight - .TextHeight(msg)) / 2
Picture1.Print msg
.Refresh
End With
End Sub

if percent=20 then

M1=msgbox ("内容",0,"标题")

end if

With Picture1
.Cls
Picture1.Line (0, 0)-(percent / 100 * .ScaleWidth, .ScaleHeight), vbGreen, BF
.CurrentX = (.ScaleWidth - .TextWidth(msg)) / 2
.CurrentY = (.ScaleHeight - .TextHeight(msg)) / 2
Picture1.Print msg
.Refresh
End With