VB .net queue strange behaviour with threads - vb.net

Question

I'm writing an vb .net form application for receiving data from commport, parsing on commport_thread and send messages to UI thread through queue.
App structure looks like this:
Private _SerialCommunicationThread As Thread
Public _DataQueue As Queue = Queue.Synchronized(New Queue())
Dim QueueLock As New Object
...
Me._SerialCommunicationThread = New Thread(AddressOf THREAD_SerialCommunication)
Me._SerialCommunicationThread.Priority = ThreadPriority.AboveNormal
Me._SerialCommunicationThread.Start()
Private Sub THREAD_SerialCommunication()
'comm port new instace, settings, start, etc
do
' copy all commport's existing bytes to rec_buffer
' parse data in rec_buffer ( my own protocol, every message has 14bytes, last is CRC sum), copy valid message (14 baytes) to buffer_work
if (CRC is OK) then
SyncLock QueueLock 'lock queue for adding message
Me._DataQueue.Enqueue(buffer_work) ' add message
'Console.WriteLine(received_messages_counter & " ID: " & buffer_work(4) & " val:" & buffer_work(5))
'buffer_work(4) is message ID byte
'buffer_work(5) is value byte
End SyncLock
end if
loop
End sub
...
'UI main thread
Private Sub Timer1_Tick ' interval=10ms
while Form1._DataQueue.Count > 0 Then
SyncLock QueueLock
buf_can = Form1._DataQueue.Dequeue()
'Console.WriteLine(received_messages_counter2 & " ID: " & buffer_work(4) & " val:" & buffer_work(5)
End SyncLock
end while
end sub
I'm sending data to COM port from microcontroler:
for(i=0,i<50;++i)
{
send_message(ID_100,i); // send message with ID=100 and data=i
send_message(ID_201,i);
send_message(ID_202,i);
};
And till parsing procedure and adding to queue console in commport thread writes exactly what is send and copy of message in buffer_work is enqueue:
1 ID: 100 val:0
2 ID: 200 val:0
3 ID: 201 val:0
4 ID: 100 val:1
5 ID: 200 val:1
6 ID: 201 val:1
...
148 ID: 100 val:49
149 ID: 200 val:49
150 ID: 201 val:49
but here comes the problem, the UI thread gives:
...
131 ID: 201 val:43
132 ID: 201 val:43
133 ID: 200 val:44
134 ID: 200 val:44
135 ID: 200 val:45
136 ID: 200 val:45
137 ID: 200 val:45
138 ID: 100 val:46
139 ID: 100 val:46
140 ID: 100 val:47
141 ID: 100 val:47
142 ID: 100 val:47
143 ID: 100 val:48
144 ID: 100 val:48
145 ID: 100 val:48
146 ID: 201 val:48
147 ID: 201 val:48
148 ID: 201 val:49
149 ID: 201 val:49
150 ID: 201 val:49
so I get exactly 150 messages but it looks like queue is enqueue in strange way...adding the same message several times, not exactly what is in buffer_work...and at the end of transmision I should have 3x49 values at 100,201 and 202 ID, but it isn't.
I thought that fifo queue behaves like enqueue A,B,C and I dequeue getting C,B,A. OK, it works but when I enqueue all messages and after that I dequeue.
When I add conditional in main UI thread:
If Form1._DataQueue.Count = 150 Then
so waiting to enqueue all 150 parsed messages in comm thread, then console prints 150 same messages received in UI thread, those all are the last sent message
...
145 ID: 201 val:49
146 ID: 201 val:49
147 ID: 201 val:49
148 ID: 201 val:49
149 ID: 201 val:49
150 ID: 201 val:49
So queue looks like to be an 1-element queue, but I need that queue will be message buffer between commport thread and UI thread, so no messaged will be lost... even if UI thread will be activ for a little longer time...
Thank you for any help and tips how to solve this problem...
Regards!