这个VB上位机程序什么地方不对？？？

Private Sub clear_receivetext_Click()
    receivetext.Text = ""
End Sub

Private Sub clear_sendtext_Click()
    sendtext.Text = ""
End Sub

Private Sub close_Click()
    MSComm1.PortOpen = False '关闭串口
    Label3 = "当前状态:关闭"
End Sub

Private Sub Form_Load()
        Label3 = "当前状态:关闭"
End Sub

Private Sub open_Click()
    MSComm1.CommPort = 4   '使用串行端口4
    MSComm1.Settings = "9600,N,8,1"    '设置波特率等
    MSComm1.InputLen = 0    '清空从接收缓存器中读到的字符
    MSComm1.PortOpen = True     '打开端口
    Label3 = "当前状态:打开"
End Sub

Private Sub send_Click()
    On Error Resume Next    '简单的错误处理
    If MSComm1.PortOpen = False Then
    MsgBox "串口已关闭"
    End If

    MSComm1.Output = sendtext.Text '将发送窗体内的文字送到单片机
    For i = 0 To Len(sendtext.Text)
    Sleep 100   '等待30毫秒,避免波特率出现的乱码
    MSComm1.Output = Mid(sendtext.Text, i, 1)
    Next i

    MSComm1.InputMode = comInputModeText    '设置接受模式是文本接受，还是二进制接受
End Sub

Private Sub shakehand_Click()
    On Error Resume Next    '简单的错误处理
    If MSComm1.PortOpen = False Then
    MsgBox "串口已关闭"
    End If

    MSComm1.Output = Chr(0)   '用EF代表发起握手
    MSComm1.InputMode = comInputModeText    '设置接受模式是文本接受，还是二进制接受

    receivetext = receivetext + vbCrLf + "正在等待握手成功信息"     '显示等待握手成功信息

    Sleep 800   '等待800毫秒
    If MSComm1.Input = Chr(1) Then
    receivetext = receivetext + MSComm1.Input + vbCrLf + "握手成功"

    Else: receivetext = receivetext + MSComm1.Input + vbCrLf + "握手失败" '用EE代表握手成功
End Sub

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