specified argument was out of the range of valid values. parameter name index

While working on a legacy ASP.NET WebForms application I stumbled into the following error: "specified argument was out of the range of valid values. parameter name index". I have a Tabcontainer with gridview filled with users fullnames and 2 ButtonField (edit & View). when I click on View with RowCommand, 5 more tabs get generated with all user information from AD. Everything works fine until I go back to the user tab and click on another user name. How can make my page remove the new 5 tabs created for the first user and add 5 new ones for the new user ?  thank you

<ajax:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server"></ajax:ToolkitScriptManager><ajax:TabContainer ID="TabContainer1"  OnInit="TabContainer1_Init" runat="server" ActiveTabIndex = "0" ScrollBars="Vertical"><ajax:TabPanel runat="server" HeaderText="Users" ID="TabPanel1"><ContentTemplate><asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" Width= "850px" Height = "650px" onrowcommand = "GridView1_RowCommand" ><Columns><asp:BoundField DataField="name" HeaderText="Name"/><asp:BoundField DataField="SamAccountName" HeaderText="Username" /><asp:BoundField DataField="EmailAddress" HeaderText="EmailAddress" /><asp:ButtonField CommandName = "View" ImageUrl ="~/Resources/Images/view.gif" ButtonType = "Image"/><asp:ButtonField CommandName = "Edit" ImageUrl ="~/Resources/Images/edit.gif" ButtonType = "Image"/></Columns></asp:GridView><Triggers><asp:AsyncPostBackTrigger ControlID="TabContainer1" EventName="ActiveTabChanged" /></Triggers></ContentTemplate>  </ajax:TabPanel></ajax:TabContainer>

 protected void Page_Load(object sender, EventArgs e)
    { if (!IsPostBack)
        {
              mydata();
        }
            }


    public void mydata()
    {
        t = Regex.Replace(ldap, @"CN=[^,]*,* *", "", RegexOptions.CultureInvariant | RegexOptions.IgnoreCase);

        try
        {

            List<string> allUsers = new List<string>();
            PrincipalContext ctx = new PrincipalContext(ContextType.Domain, "IDEA.COM", t);
            UserPrincipal usr = new UserPrincipal(ctx);


            // Create a PrincipalSearcher object.
            PrincipalSearcher ps = new PrincipalSearcher(usr);
            PrincipalSearchResult<Principal> fr = ps.FindAll();
            GridView1.DataSource = fr;

            GridView1.DataBind();
        }
        catch (Exception ex)
        {
        }
    }
 protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
    {
         int row = int.Parse(e.CommandArgument.ToString());
                item = GridView1.Rows[row].Cells[1].Text;
                var username = GridView1.Rows[row].Cells[0].Text;
                string firstname = username.Remove(username.IndexOf("."));
                DirectoryEntry de = new DirectoryEntry();
                de.Path = "LDAP://idea.com";
                DirectorySearcher objADSearcher = new DirectorySearcher(de);
                de.AuthenticationType = AuthenticationTypes.Secure;
                objADSearcher.SearchRoot = de;
                objADSearcher.Filter = "(SAMAccountName=" + item + ")";
                SearchResult results = objADSearcher.FindOne();            
            if (e.CommandName == "View")
            { if (results.ToString() != "") {int flags = Convert.ToInt32(results.Properties["userAccountControl"][0].ToString());
 if (Convert.ToBoolean(flags & 0x0002)){Response.Write("<script> alert ('" + "Account Disabled for more then 90 days" + "') </script>");
           else
                    {WindowsIdentity wi = new WindowsIdentity(item);
  foreach (IdentityReference group in wi.Groups)
              {
             try
               {
     result1.Add(group.Translate(typeof(NTAccount)).ToString());
        result1.Sort();
               }
   catch (Exception ex) { }
                        }
  string tabid;
    AjaxControlToolkit.TabPanel apptab = new AjaxControlToolkit.TabPanel();
   apptab.HeaderText = firstname + " " + "Application";
apptab.ID = string.Format("Tab{0}{1}",suffix, "tab1");
  AjaxControlToolkit.TabPanel sharedtab = new AjaxControlToolkit.TabPanel();
 sharedtab.HeaderText = firstname + " " + "SharedCommon"; 
sharedtab.ID = string .Format ("Tab{0}{1}",suffix ,"tab2" );
AjaxControlToolkit.TabPanel grouptab = new AjaxControlToolkit.TabPanel();
grouptab.HeaderText = firstname + " " + "Internet/RAS";
grouptab.ID = string.Format("Tab{0}{1}",suffix, "tab3");
    AjaxControlToolkit.TabPanel idtab = new AjaxControlToolkit.TabPanel();
idtab.HeaderText = firstname + " " + "Info";
  idtab.ID = string.Format("Tab{0}{1}",suffix, "tab4");
                TabContainer1.Tabs.Add(grouptab);
                        TabContainer1.Tabs.Add(apptab);
                        TabContainer1.Tabs.Add(sharedtab);
                        TabContainer1.Tabs.Add(idtab);
}}}