VB.NET: Problem with too large XML data

[toytoy]

Say when i click on "A" button, my program will receive the large XML data for "A" from the server...

1) However, i will only receive one section of data....
2) Then when i continue to click on "B" button, it will not receive "B" data
instead it will continue to receive the rest of "A" data...

My coding for receiving the data....

Dim tcpC As New TcpClient
Public Function receive() As String

 Dim ascii As Encoding = Encoding.ASCII
 Dim networkStream As NetworkStream
 Try
   networkStream = tcpC.GetStream()
   Dim bytes(tcpC.ReceiveBufferSize) As Byte
   networkStream.Read(bytes, 0, CInt(tcpC.ReceiveBufferSize))
   Dim ret As String = ascii.GetString(bytes)
   Return ret
 Catch
 End Try
End Function

How to solve the problem of getting large data...

Thanks