c# - ランタイム テキストボックスの作成で問題が発生する

Question

このコードは最初の 2 回は正常に動作します。つまり、[ソリューションを追加] をクリックすると、それぞれ新しい行とコントロールが作成されますが、3 回目に [ソリューションを追加] をクリックし、それぞれの [ステップを追加] ボタンをクリックすると、それは、、、それは問題を作成します。

protected void Page_Load(object sender, EventArgs e)
{

        for (int i = 0; i < TotalNumberAdded; i++)
        {
            AddControls((i + 1), plcSolution);
        }
        for (int i = 0; i < TotalNumberSolAdded; i++)
        {

            AddMoreControls((i + 1), plcAddMoreSolution, 1);
            Button b = (Button)plcAddMoreSolution.FindControl("btn" + (i+1));

            for (int j = 0; j < TotalNumberSolStepAdded; j++)
            {

                AddMoreStepControls((j + 1), plcAddMoreSolution);
            }
        }


}



protected void btnAdd_Click(object sender, EventArgs e)
{


        TotalNumberAdded++;
        AddControls(TotalNumberAdded, plcSolution);

}
private void AddControls(int controlNumber, PlaceHolder plc)
{
        TextBox txtBoxSolution = new TextBox();
        Label lblSolution = new Label();

        txtBoxSolution.ID = "txtBoxSolution" + controlNumber;
        txtBoxSolution.TextMode = TextBoxMode.MultiLine;

        txtBoxSolution.Width = 470;
        txtBoxSolution.Height = 50;
        lblSolution.ID = "lblSolution" + controlNumber;

        lblSolution.Text = "Step " + (controlNumber + 1) + ": ";
        lblSolution.Width = 200;


        plc.Controls.Add(lblSolution);

        plc.Controls.Add(txtBoxSolution);



}

protected int TotalNumberAdded
{

    get { return (int)(ViewState["TotalNumberAdded"] ?? 0); }
    set { ViewState["TotalNumberAdded"] = value; }
}


protected void btnAlternate_Click(object sender, EventArgs e)
{
    lblSol.Text = "Solution 1";
    string str = (string)ViewState["btnId"];
    if (str != null)
    {
        btn = (Button)plcAddMoreSolution.FindControl(str);

        btn.Visible = false;

    }

    btnAdd.Visible = false;
    TotalNumberSolAdded++;
    AddMoreControls(TotalNumberSolAdded, plcAddMoreSolution,1);

}
protected int TotalNumberSolAdded
{

    get { return (int)(ViewState["TotalNumberSolAdded"] ?? 0); }
    set { ViewState["TotalNumberSolAdded"] = value; }
}
private void AddMoreControls(int controlNumber, PlaceHolder plc,int n)
{

        TextBox txtBoxMoreSolution = new TextBox();

        Label lblMoreSolution = new Label();
         btn = new Button();
        btn.Text = "add step";
        btn.ID = "btn" + controlNumber;
        btn.Click += new EventHandler(btn_Click);
        ViewState["btnId"] = btn.ID;
        Label lbl = new Label();
        lbl.Text = "soltuion" + (controlNumber + 1);
        lbl.ID = "moreSolution" + (controlNumber + 1);
        lbl.Font.Size = 20;
        lbl.Font.Underline = true;

        txtBoxMoreSolution.ID = "txtBoxMoreSolution" + controlNumber;
        txtBoxMoreSolution.TextMode = TextBoxMode.MultiLine;

        txtBoxMoreSolution.Width = 470;
        txtBoxMoreSolution.Height = 50;
        lblMoreSolution.ID = "lblMoreSolution" + controlNumber;

        lblMoreSolution.Text = "Step " + n + ": ";
        lblMoreSolution.Width = 200;



        plc.Controls.Add(lbl);

        plc.Controls.Add(lblMoreSolution);

        plc.Controls.Add(txtBoxMoreSolution);

        plc.Controls.Add(btn);



}

private void btn_Click(object sender, EventArgs e)
{
    TotalNumberSolStepAdded++;
    AddMoreStepControls(TotalNumberSolStepAdded, plcAddMoreSolution);
}

protected int TotalNumberSolStepAdded
{

    get { return (int)(ViewState["TotalNumberSolStepAdded"] ?? 0); }
    set { ViewState["TotalNumberSolStepAdded"] = value; }
}

private void AddMoreStepControls(int controlNumber, PlaceHolder plc)
{

        TextBox txtBoxMoreStepSolution = new TextBox();
        Label lblMoreStepSolution = new Label();

        txtBoxMoreStepSolution.ID = "txtBoxMoreStepSolution" + controlNumber;
        txtBoxMoreStepSolution.TextMode = TextBoxMode.MultiLine;

        txtBoxMoreStepSolution.Width = 470;
        txtBoxMoreStepSolution.Height = 50;
        lblMoreStepSolution.ID = "lblMoreStepSolution" + controlNumber;

        lblMoreStepSolution.Text = "Step " + (controlNumber +1) + ": ";
        lblMoreStepSolution.Width = 200;


        plc.Controls.Add(lblMoreStepSolution);

        plc.Controls.Add(txtBoxMoreStepSolution);


}