通过socket与UNIX主机进行通信，单个用户查询没问题，两个或两个以上用户同时进行查询，查询时间分别为30秒，第一个用户查询10秒后，第二个用户开始查询，两个用户得到的结果都是第一个用户的，或者第一个查不到，第二个查询显示的是第一个的查询结果，求原因。
client端：

Private Function Receive(ByRef state As StateObject, ByVal Merch_ID As String, ByVal ULNm As String) As Boolean 
        On Error GoTo go_Err
        Dim readStream As New NetworkStream(state.workSocket)
        Dim blnReturn As Boolean = False
        Dim intRcv As Integer
        Dim strTmp As String = ""
  
        state.buffer.Clear(state.buffer, 0, StateObject.BufferSize)
        readStream.ReadTimeout = iTimeOutM
        intRcv = readStream.Read(state.buffer, 0, StateObject.BufferSize)
  
        Do While intRcv > 0
            strTmp = Encoding.Default.GetString(state.buffer, 0, intRcv)
            state.sb.Append(strTmp)
  
            If ConfigurationManager.AppSettings("g_IsDebug") = "1" Then
                Dim FileToWrite As  = ("D:\程序\ESA_OPR_New\debug\Receive" + Merch_ID + "_" + ULNm + ".txt")
                Dim rByte() As Byte = Encoding.Default.GetBytes(state.sb.ToString.ToCharArray)
                FileToWrite.Write(rByte, 0, rByte.Length)
                FileToWrite.Close()
                FileToWrite = Nothing
            End If
  
            '不按照报文头字符长度来取报文体字段，因为在测试中发现WINDOWS与UNIX在中文和特殊字符的长度判断上不相同
            '所以采用查找结束符号的方式来判断报文尾
            If InStr(strTmp, "</PACKAGE>") > 0 Then
                Exit Do
            Else
                state.buffer.Clear(state.buffer, 0, StateObject.BufferSize)
                intRcv = readStream.Read(state.buffer, 0, StateObject.BufferSize)
            End If
        Loop
        blnReturn = True
        readStream = Nothing
go_Exit:
        Return blnReturn
        Exit Function
go_Err:
        blnReturn = False
        GoTo go_Exit
    End Function