没有加载返回的表单值

我使用Firebug进行验证，并且我的回调成功触发。在"Post"部分，它显示我的TextBox(更确切地说，是为我的文本框呈现的HTML)成功提交了它的表单值(无论在文本框中输入了什么)。然而，在服务器端，该值没有被恢复到新创建的TextBox中——即使我重新创建的所有内容都具有与最初相同的ID。此外，我检查了Page.Request.Form集合(参见:getcontrolashhtml())和我尝试的所有事情都没有返回我的值。这是代码，感谢任何帮助。

我的目标是执行回调(当前工作)，并恢复我的文本框的值从张贴回来的表单值(不工作)。为简洁起见，省略了一些(可工作的)代码。

public class CreateForm : WebPart, ICallbackEventHandler
{
    public string callbackData = "";
    public DropDownList list = new DropDownList();
    public Panel p = new Panel();
    public virtual string GetCallbackResult()
    {
        return callbackData;
    }
    protected override void OnInit(EventArgs e)
    {
        base.OnInit(e);
            //The DropDownList is created here in my real code, but was omitted
            //because it is working as expected.
            //At the moment, all the DDL does is cause a callback to occur.
        p.ID = "theForm";
        if (!Page.IsPostBack) 
        {
            MyForm MyForm = new MyForm();
            MyForm.ID = "currentForm";
            p.Controls.Add(MyForm);
        }
        Controls.Add(p);  
    }
    /*
     * The eventArgument field is parsed to get the desired command.
     * Valid commands:
     * 1) send - Indicates the user has clicked the 'send' button. 
     * 2) display - Indicates the user wants to change the form
     *              currently displayed.
     *    A drop down box is used to let the user choose the form. 
     */
    public virtual void RaiseCallbackEvent(string eventArgument)
    {
                if (eventArgument.StartsWith("display"))
            {
                //always index 0 for testing. 
                callbackData = CreateFormByType(0);
                }
    }
    public string CreateFormByType(int index)
    {
        MyForm test = null;
        switch (index)
        {
            case 0:
                test = new MyForm();
                break;
        }
        if (test != null)
        {
            test.ID = "currentForm";
            p.Controls.Add(test);
        }
        return test != null ? test.getControlAsHtml() : null;
    }
}
public class MyForm : Control
{
    public Label label = new Label();
    public TextBox textboxForLabel = new TextBox();
    protected override void OnInit(EventArgs e)
    {
            base.OnInit(e);
        textboxForLabel.ID = "textboxForLabel";
        label.AssociatedControlID = "textboxForLabel";
        label.Text = "textboxForLabel: ";
        this.Controls.Add(label);
        this.Controls.Add(textboxForLabel);
    }
    public virtual string getControlAsHtml()
    {
            //How come all 3 of these don't return the expected value?
        string s = Page.Request.Form[textboxForLabel.ID];
        string t = Page.Request.Form[textboxForLabel.ClientID];
        textboxForLabel.Text = (string)Page.Request.Form["textboxForLabel"];
        StringBuilder sb = new StringBuilder();
        using (StringWriter sw = new StringWriter(sb))
        {
            using (HtmlTextWriter textWriter = new HtmlTextWriter(sw))
            {
                this.RenderControl(textWriter);
            }
        }
        return sb.ToString();
    }
}