Not getting a desired tree view using asp treeview in asp.net using c#?

i have a tree view :

 <asp:TreeView ID="testtree1" runat="server" OnSelectedNodeChanged="testtree1_SelectedNodeChanged">
     <Nodes>
        <asp:TreeNode Expanded="False" Text="Tests" Value="Tests"></asp:TreeNode>
     </Nodes>
 </asp:TreeView>

i in my .cs file i have this code:

protected void testtree1_SelectedNodeChanged(object sender, EventArgs e)
    {
        if (testtree1.SelectedNode.Text == "Tests")
        {
            con.Open();
            SqlCommand cmdd = new SqlCommand("select count(Name) from TypeOfWork");
            cmdd.Connection = con;
            int idcount = Convert.ToInt32(cmdd.ExecuteScalar());
            SqlCommand cmd = new SqlCommand("select Name from TypeOfWork");
            cmd.Connection = con;
            string[] nid = new string[idcount];
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            DataSet ds = new DataSet();
            da.Fill(ds);

            if (ds.Tables[0].Rows.Count > 0)
            {
                for (int i = 0; i < idcount; i++)
                {
                    nid[i] = ds.Tables[0].Rows[i]["Name"].ToString().Trim();
                    testtree1.Nodes.Add(new TreeNode(nid[i]));
                }
            }
        }
        else
        {
            string tstr = testtree1.SelectedNode.Text;
            con.Open();
            SqlCommand cmd = new SqlCommand("select TypeOfWorkID from TypeOfWork where Name='" + tstr + "'");
            cmd.Connection = con;
            int tid = Convert.ToInt32(cmd.ExecuteScalar());

            SqlCommand cmdd = new SqlCommand("select count(Name) from CategoryLevel1 where TypeOfWorkID='" + tid + "'");
            cmdd.Connection = con;
            int idcount = Convert.ToInt32(cmdd.ExecuteScalar());
            SqlCommand cmd1 = new SqlCommand("select Name from CategoryLevel1 where TypeOfWorkID='" + tid + "'");
            cmd1.Connection = con;
            string[] nid = new string[idcount];
            SqlDataAdapter da = new SqlDataAdapter(cmd1);
            DataSet ds = new DataSet();
            da.Fill(ds);
            if (ds.Tables[0].Rows.Count > 0)
            {
                for (int i = 0; i < idcount; i++)
                {

                    nid[i] = ds.Tables[0].Rows[i]["Name"].ToString().Trim();
                    TreeNode child1 = new TreeNode();
                    child1.Text = nid[i];
                    testtree1.Nodes.Add(child1);
                }
            }
        }



    }

the problem here is i am getting a tree getting the correct data but not getting the tree view as it should be.

the root is Tests when i am clicking it i am getting Civil and RVI but they are not as tree view they are comming under the tests

and when i am clicking Civil or RVI its childnodes are coming under the whole thing not as a normal tree ... what to do?

any help