VB制作倒计时器问题

Option Explicit Dim h As Integer, m As Integer, s As Integer Private Sub Command1_Click() If Not IsNumeric(Text1.Text) Then MsgBox "请正确小时数！" Exit Sub End If If Not IsNumeric(Text2.Text) Then MsgBox "请正确分钟数！" Exit Sub End If If Not IsNumeric(Text3.Text) Then MsgBox "请正确秒数！" Exit Sub End If h = Text1.Text m = Text2.Text s = Text3.Text If m >= 60 Then MsgBox "分钟数必须小于60！" Exit Sub End If If s >= 60 Then MsgBox "秒数必须小于60！" Exit Sub End If Timer1.Ena