VB6 Winsock receiving NULL error?

[levisvv]

I am creating an interface program to connect to a Panasonic PBX.
I am using VB6 with the Winsock control.

I can connect to the PBX's IP address/port OK and it accepts my connection.

I can send the initial connection string to the PBX as follows:

Mtosend = Chr$(&H0) & Chr$(&H25) & Chr$(&H60) & Chr$(&H23) & Chr$(&H80) & Chr$(&H2) & Chr$(&H7) & Chr$(&H80) & Chr$(&HA1) & Chr$(&H7) & Chr$(&H6) & Chr$(&H5) & Chr$(&H2B) & Chr$(&HC) & Chr$(&H0) & Chr$(&H81) & Chr$(&H5A) & Chr$(&HBE) & Chr$(&H14) & Chr$(&H28) & Chr$(&H12) & Chr$(&H6) & Chr$(&H7) & Chr$(&H2B) & Chr$(&HC) & Chr$(&H0) & Chr$(&H82) & Chr$(&H1D) & Chr$(&H81) & Chr$(&H48) & Chr$(&HA0) & Chr$(&H7) & Chr$(&HA0) & Chr$(&H5) & Chr$(&H3) & Chr$(&H3) & Chr$(&H0) & Chr$(&H8) & Chr$(&H0)
Winsock1.SendData Mtosend

When I monitor the TCP packets using WireShark, I can see that the phone switch acepted my packet properly and sent the proper 51-byte reply, but when I try to read the reply data in Winsock, it informs me that 51 bytes have been received OK, but the received data (read as a string) shows as a "null" string.
If I use the following code to retrieve the 51 byte data into a byte array, I get 51 zero's - in Wireshark I can see that the data packet only started with 0 (null) but the rest looked like valid data.

Private Sub Winsock1_DataArrival(ByVal bytesTotal As Long)
Dim DL As String
Dim DTS As String
Dim byteData(256) As Byte
Dim i As Integer
DL = CStr(bytesTotal)
DTS = ""
Winsock1.GetData byteData(), vbArray + vbByte, Val(Trim(DL))
For i = 0 To bytesTotal - 1
    DTS = DTS & " " & Right$(("00" & Hex$(byteData(i))), 2)
Next
SaveLog "TCP Rx: " & DTS & "  (bytes=" & DL & ")"
Exit Sub

Please help - how can I get the proper data?

What am I doing wrong?