how to get selected item value in gridview in datalist

[erum]

see teh code

<asp:DataList ID="DataList1" runat="server"   Width="200%" > 

    <ItemTemplate>
        <h4><asp:Label ID="DAtes" runat="server"       Text='<%# Eval("date") %>'></asp:Label></h4>
           
           
         <asp:GridView  AllowPaging=True   ID="GridView1" runat="server" 
                                                      DataKeyNames=sessionid 
                                                      AutoGenerateColumns="False" CellPadding="4" 
                                                      Width="697px" 
            style="margin-right: 0px" ForeColor="#333333" GridLines="None">
                                                  <RowStyle ForeColor="#333333" BackColor="#F7F6F3" />
                                                         <Columns>
                                                            <asp:TemplateField HeaderText="Availability">
    <ItemTemplate>
        <asp:CheckBox ID="chkgfln" Enabled=true runat="server" Text=Available  />
       
    </ItemTemplate>
       
</asp:TemplateField>
  <asp:BoundField HeaderText="sessionid" DataField=sessionid />
  
  <asp:BoundField HeaderText="userid" DataField=userid />
           
           <asp:BoundField HeaderText="Start Time" DataField=starttime />
           <asp:BoundField HeaderText="end Time" DataField=endtime />
           
           <asp:TemplateField HeaderText="send invitation">
          <ItemTemplate>
          <asp:ImageButton   OnClick="deleteIL_Click" commandargument="'<%# />'"
                                        ID="imgedit1" runat="server" 
                                        ImageUrl="~/images/email.gif" />
          </ItemTemplate>
          </asp:TemplateField>
          
             

          </Columns> 

                                                  <FooterStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />
                                                  <PagerStyle BackColor="#284775" ForeColor="White" HorizontalAlign="Center" />
                                                  <SelectedRowStyle BackColor="#E2DED6" Font-Bold="True" ForeColor="#333333" />
                                                  <HeaderStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />
                                                  <EditRowStyle BackColor="#999999" />
                                                  <AlternatingRowStyle BackColor="White" ForeColor="#284775" />

</asp:GridView> 
          </ItemTemplate>
       
    </asp:DataList>

and i code behind i ahve

Protected Sub deleteIL_Click(ByVal sender As Object, ByVal e As ImageClickEventArgs)
        Try
            Dim lnkBtn As ImageButton = DirectCast(sender, ImageButton)

            'Dim _UnlockID As Integer = Integer.Parse(lnkBtn.CommandArgument)

            Dim dsphonUnloack As New DataSet()
            Dim ts As New EmailManager
            Dim ex As New ExecuteTSQL

            ts.EmailToclient2(ViewState("username"), ViewState("email").ToString(), Session("login").ToString())
            ' ex.IUD ("update user_session set approve=1 where sessionid= " & Convert.ToInt32 (  ViewState("Sessionid")) & " and userid= " & Convert.ToInt32 (ViewState("userid")) &  ")
            'ex.IUD("update user_session set approve= " & 1 & " , senderuserid = " & Convert.ToInt32(Session("Loginuserid").ToString()) & "  ,sendingdatetime =   " & DateTime.Now & " Where userid = " & Convert.ToInt32(ViewState("userid")) & "  and sessionid= " & Convert.ToInt32(ViewState("Sessionid")))
            ex.IUD("update user_session set status= " & 1 & " , senderuserid = " & Convert.ToInt32(Session("Loginuserid").ToString()) & "  ,sendingdatetime =     ' " & DateTime.Now & " '" & " Where userid = " & Convert.ToInt32(ViewState("userid")) & "  and sessionid= " & Convert.ToInt32(ViewState("Sessionid")))

                  Catch
        End Try

    End Sub

i want to get sessionid of row when imagebutton is clicked ,any urgent reply is higly appreciated