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