vb.net Hashtable保存skcoet问题

Question

Imports System.Net.Sockets
Imports System.Net
Imports System.Threading

Public Class Form1
Dim bin_buf(1024) As Byte
Dim id_socket As New Hashtable
Dim s As New Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp)
Dim localEndPoint As IPEndPoint
Dim send_socket As New Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp)

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    Button1.Enabled = False
    bin_buf(0) = 1
    bin_buf(1) = 2
    bin_buf(2) = 3
    Dim t As New Thread(AddressOf accept_link)
    t.Start()
End Sub

Private Sub accept_link()
    localEndPoint = New IPEndPoint(IPAddress.Parse("127.0.0.1"), Val(TextBox1.Text)) ' '''指定IP和Port

    Try
        s.Bind(localEndPoint)   ' '''绑定到该Socket
    Catch

        '提示端口被占用
        MsgBox("端口被占用")

        End

    End Try

    s.Listen(100)  ''''侦听，最多接受100个连接

    Do
        Dim new_s As Socket = s.Accept()

        Dim t As New Thread(AddressOf process_sub)
        t.Start(new_s)
    Loop
End Sub

Private Sub process_sub(ByVal s As Socket)

    Dim buf(1023) As Byte
    Dim sbuf(1) As Byte
    Dim l As Long

    Do
        l = s.Receive(buf)

        If l > 0 Then

            If l = 1 Then
                If id_socket.ContainsKey(buf(0).ToString) = False Then
                    id_socket.Add(buf(0).ToString, s)
                End If

                send_socket = s
            End If

        Else
            s.Close()
            Exit Do
        End If
    Loop

End Sub

Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
    Dim s As String = ""

    For Each i As DictionaryEntry In id_socket
        s &= "ID:" & i.Key & "  socket:" & i.Value.ToString & vbCrLf
    Next

    TextBox2.Text = s
End Sub

Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
    Dim s As String

    s = TextBox3.Text

    If id_socket.ContainsKey(s) = True Then
        Dim ss As Socket
        Dim buf(0 To 6)

        buf(0) = &H68
        buf(1) = &H65
        buf(2) = &H6C
        buf(3) = &H6C
        buf(4) = &H6F
        buf(5) = &HD
        buf(6) = &HA

        ss = CObj(id_socket.Item(s))

        ss.Send(buf)
    End If
End Sub

Private Sub Button4_Click(sender As Object, e As EventArgs) Handles Button4.Click

    Dim buf(0 To 6)

    buf(0) = &H68
    buf(1) = &H65
    buf(2) = &H6C
    buf(3) = &H6C
    buf(4) = &H6F
    buf(5) = &HD
    buf(6) = &HA

    send_socket.Send(buf)
End Sub

End Class

运行到ss.endf(buf)报错：
System.InvalidCastException:“无法将类型为“System.Object[]”的对象强制转换为类型“System.Collections.Generic.IList1[System.ArraySegment1[System.Byte]]”。”

是Hashtable无法保存socket对象，还是程序哪写的不对。还请懂的赐教