B4R Question Arduino upload sketch error

Hello all,
After a long time, today I thought I can play with B4R and used to LED example project. but I got the following error:
=====================
B4R Version: 2.51
Parsing code. (0.00s)
Compiling code. (0.21s)
Building project (0.79s)
Compiling & deploying Ino project (Arduino/Genuino Uno - COM8) Error
Loading configuration...
Initializing packages...
Preparing boards...
Verifying...
Uploading...
avrdude: Version 6.3, compiled on Jan 17 2017 at 12:00:53
Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
Copyright (c) 2007-2014 Joerg Wunsch
System wide configuration file is "C:\Arduino\B4R\Arduino\hardware\tools\avr/etc/avrdude.conf"
Using Port : COM8
Using Programmer : arduino
Overriding Baud Rate : 115200
avrdude: ser_open(): can't open device "\\.\COM8": The semaphore timeout period has expired.


avrdude done. Thank you.
An error occurred while uploading the sketch
===============================

And this is the code:
Hello all,
After a long time, today I thought I can play with B4R and used to LED example project. but I got the following error:
=====================
B4R Version: 2.51
Parsing code. (0.00s)
Compiling code. (0.21s)
Building project (0.79s)
Compiling & deploying Ino project (Arduino/Genuino Uno - COM8) Error
Loading configuration...
Initializing packages...
Preparing boards...
Verifying...
Uploading...
avrdude: Version 6.3, compiled on Jan 17 2017 at 12:00:53
Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
Copyright (c) 2007-2014 Joerg Wunsch
System wide configuration file is "C:\Arduino\B4R\Arduino\hardware\tools\avr/etc/avrdude.conf"
Using Port : COM8
Using Programmer : arduino
Overriding Baud Rate : 115200
avrdude: ser_open(): can't open device "\\.\COM8": The semaphore timeout period has expired.


avrdude done. Thank you.
An error occurred while uploading the sketch
===============================

And this is the code:
<CODE>

#Region Project Attributes
#AutoFlushLogs: True
#CheckArrayBounds: True
#StackBufferSize: 300
#End Region

Sub Process_Globals
Public Serial1 As Serial
Private pinButton As Pin 'pin for the button
Private pinLEDGreen As Pin 'pin for the green Led
Private LightOn = False As Boolean
End Sub

Private Sub AppStart
Serial1.Initialize(115200)

'Using the internal pull up resistor to prevent the pin from floating.
pinButton.Initialize(pinButton.A5, pinButton.MODE_INPUT_PULLUP)
pinButton.AddListener("pinButton_StateChanged")

pinLEDGreen.Initialize(7, pinLEDGreen.MODE_OUTPUT)
End Sub

Private Sub pinButton_StateChanged (State As Boolean)
If State = False Then 'remember, False means button pressed.
LightOn = Not(LightOn)
pinLEDGreen.DigitalWrite(LightOn)
End If
End Sub
</CODE>