HELP! ViewState / OnInit() Dyanamic Textboxes

QUESTION: How can I maintain the viewstate of a panel that contains dynamically created formfields?

SCENARIO:

My Page is laid out like this (psuedo code) :

Page_Load()
{
  if (!IsPostBack){
   ...Connect to DB and get Categories
   ...Bind them to a DropDownList
  }
}
------ In the Form:
<asp:DropDownList ID="Category" AutoPostBack="true" OnSelectedIndexChanged="ShowSubcategories" runat="server"/>
-----------

void ShowSubcategories()
{
...Connect to DB and get all Subcategories related to the selected Category
...Bind them to a second DropDownList
}

------ In the Form:
<asp:DropDownList ID="Subcategory" AutoPostBack="true" OnSelectedIndexChanged="ShowPanel" runat="server"/>
-----------

void ShowPanel()
{
...Connect to DB
...Get however many detailIDs there are associated with the selected Subcategory and create dynamic texboxes.
...Add these to a asp:Panel inside part of a Form

  while (dr3.Read())
    {
     TextBox tBox=new TextBox();
     tBox.ID="frm"+dr3[0].ToString();
     tBox.CssClass="textfield_grey";
     tBox.Columns=35;
   
     form1.Controls.Add(tBox);
     myPanel.Controls.Add(tBox);
   }
}

-------- Finally in the Form:--------

<asp:Button ID="btnSubmit" Text="Submit" OnClick="GetPanelText" runat="server"/>
------------------------------------

void GetPanelText()
{
 ...this is where I am trying to see if the textboxes are still there with Response.Write something but I don't get output because I need to do something with ViewState.

   foreach (Control ctl in myPanel.Controls)
   {    
     Response.Write("yes");
    }
  }
}