Android Question Release of buffer Astreams_Newdata

Sub send2
If AStreams.IsInitialized = False Then Return
     ' both rx_challenge and tx_challenge are declared in Globals
   Log("challenge in buffer BEFORE 'asking for CHALLENGE' is send"&rx_challenge)
   tx_challenge="<c>ask for challenge</c>"
    Dim buffer1() As Byte
     buffer1=tx_challenge.GetBytes("UTF8")
     AStreams.Write(buffer1)
     Log("challenge send: "&tx_challenge)   
     ' this is the main code. I Did try
     ' to split this in 2 service modules
     ' and with a timer between "challenge send"
     ' and "received challenge"
   Log("received challenge in buffer "&rx_challenge)
   ' here I just echo the received rx_challenge
   ' In the productionversion rx_challenge is recalculated
   ' based on the original rx_challenge
   msg="<c>response: "&rx_challenge&"</c>"
     buffer1 =msg.GetBytes("UTF8")
   AStreams.Write(buffer1)
     Log("response send by B4A: "&msg)
   Log ("nothing received")   
End Sub

Sub AStreams_NewData (buffer() As Byte)
   
  rx_challenge = BytesToString(buffer, 0, buffer.Length, "UTF8")
  Log(" received challenge in Newdata: "&rx_challenge)
End Sub