Android Question Stopping a service

Sub Process_Globals
    'These global variables will be declared once when the application starts.
    'These variables can be accessed from all modules.
    Dim Timer1 As Timer
      Timer1.Initialize("Timer1",1000)

End Sub
Sub Globals
    'These global variables will be redeclared each time the activity is created.
    'These variables can only be accessed from this module.
    Dim n As Notification
    Dim btnStartS As Button
    Dim btnStopS As Button
    Dim Label1 As Label
End Sub
Sub Activity_Create(FirstTime As Boolean)
    'Do not forget to load the layout file created with the visual designer. For example:
    Activity.LoadLayout("test")
End Sub
Sub Activity_Resume
End Sub
Sub Activity_Pause (UserClosed As Boolean)
    StopService(Serial)
    Activity.Finish
End Sub
Sub Timer1_Tick
    'Update service counter value
      Label1.Text=Serial.Counter
End Sub
Sub btnStartS_Click
    'Start the service
    Timer1.Enabled=True
    StartService(Serial)
End Sub
Sub btnStopS_Click
    'Stop the service
    Timer1.Enabled=False
    StopService(Serial)
End Sub

Sub Process_Globals
    'These global variables will be declared once when the application starts.
    'These variables can be accessed from all modules.
    Dim beep As Beeper
    Dim nSer As Notification
    Dim Counter As Int
End Sub
Sub Service_Create
    Counter=0
    nSer.Initialize
    beep.Initialize(100, 1000) '100 milliseconds, 1Khz
End Sub

Sub Service_Start (StartingIntent As Intent)
    'Start service evry x seconds
    'StartServiceAt("", DateTime.Now + 10 * DateTime.TicksPerSecond, True)
    'Service.StartForeground(1,nSer)
    StartServiceAt("", DateTime.Now + 3 * DateTime.TicksPerSecond, True)
   
    'Service notification
    nSer.Icon = "icon"
    nSer.Vibrate = False
    nSer.Sound = False
    nSer.SetInfo("MyApp","Service Running",Main)
    nSer.OnGoingEvent = False
    nSer.Light = True
    nSer.Notify(1)
    Counter=Counter+1 ' This counting will not work for long. If it is important it should be saved in a file instead of a variable.
   
    beep.beep
End Sub
Sub Service_Destroy
    nSer.Cancel(1)
End Sub