为什么VB接收不到串口来的数据

[fyhx9999]

Private Sub Form_Load()
If MSComm1.PortOpen = False Then
MSComm1.PortOpen = True
End If
Text1.Text = ""
End Sub

Private Sub MSComm1_OnComm()
Select Case MSComm1.CommEvent
Case comEvReceive '...有接收事件发生
Text1.Text = Val(MSComm1.Input)
End Select
End Sub

Private Sub Timer1_Timer()
Select Case Text1.Text
Case "01"
Text1.Text = "01"
SendKeys "a"
Case "02"
Text1.Text = "02"
SendKeys "b"
End Select
End Sub
串口助手能接收到数据01 02. 下位机发送01,02