How to dynamically generate controls in datalist and access them in C#?

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C#

ASM

I have a datalist and in that there is a button whoes ID="btnComment". when clicked on this button controls should be dynamically generated and added to panel named "PlComment".
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ASPX code:
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<asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager>
                         <asp:UpdatePanel ID="UpdatePanel1" runat="server">
                              <ContentTemplate>
                                  <asp:DataList ID="dlAnswers" runat="server" RepeatColumns="1" RepeatDirection="Vertical">

                                 <ItemTemplate>
                                  <div class="comment-body comment-body-answered clearfix">
                             <div class="avatar">
                                 <asp:Image ID="ProfileImg" runat="server" ImageUrl='<%#Eval("ProfileImg") %>' />
                             </div>
                             <div class="comment-text">
                                 <div class="author clearfix">
                                     <div class="comment-author"><a href='<%#Eval("FirstName")+" "+Eval("LastName") %>'></a></div>
                                     <div class="comment-vote">
                                         <ul class="question-vote">
                                             <li><a href="#" class="question-vote-up" title="Like"></a></li>
                                             <li><a href="#" class="question-vote-down" title="Dislike"></a></li>
                                         </ul>
                                     </div>
                                     <span class="question-vote-result">+1</span>
                                     <div class="comment-meta">
                                         <div class="date"><i class="icon-time"></i><%#Eval("AnsDate") %>

                                          </div>
                                          <a class="button small green-button" href="#" style="float:right;padding:5px 15px; margin-left:300px">Accept Solution</a>
                                     </div>

                                 </div>
                                 <div class="text">
                                     <asp:Label ID="lblAnswer" runat="server" Text='<%#Eval("Description")%>'></asp:Label></p>
                                 </div>
                                 <div id="AnsCommentBox" class="question-answered question-answered-done">

                                    <%-- <i class="icon-comments"></i>--%>
                                   <%--  <input type="button" value="Have a Comment?" class="button btn btn-small" onclick="CreateControls()" />--%>
                                     <div id="divComment">

                                     </div>

                                    </div>
                             </div>
                         </div>

                             </ItemTemplate>
                      </asp:DataList>


                                     <asp:Button ID="btnComment" runat="server" Text="Have a Comment?" CssClass="button btn btn-small" OnClick="PostComment" />
                                       <asp:Panel ID="PlComment" runat="server" ></asp:Panel>
                                     </ContentTemplate>
                             </asp:UpdatePanel>

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C# code
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protected void PostComment(object sender,EventArgs e)
      {
          TextBox txtAnswerComment = new TextBox();
          Button btnSubmit = new Button();
          Button btnCancel = new Button();
          btnSubmit.Text = "Submit";
          btnCancel.Text = "Cancel";
          btnCancel.Style.Add("font-size", "12px;");
          btnCancel.Style.Add("Padding", "4px 10px;");
          btnCancel.Style.Add("font-size", "12px;");
          btnSubmit.Style.Add("Padding", "4px 10px;");

          btnSubmit.Attributes.Add("class", "button small blue-button");
          btnSubmit.Attributes.Add("runat", "server");
          btnSubmit.Style.Add("font-size", "12px");
          btnCancel.Attributes.Add("class", "button small red-button");
          btnCancel.Attributes.Add("runat", "server");

          txtAnswerComment.ID = "txtAnswerComment";
          txtAnswerComment.TextMode = TextBoxMode.MultiLine;
          txtAnswerComment.Style.Add("Width","700px;");
          txtAnswerComment.Style.Add("Height", "80px;");
          txtAnswerComment.Attributes.Add("runat", "server");
          txtAnswerComment.Font.Size = 9;
          txtAnswerComment.Style.Add("resize", "none;");

          PlComment.Controls.Add(txtAnswerComment);
         PlComment.Controls.Add(btnSubmit);
          PlComment .Controls.Add(btnCancel);
          btnCancel.Click += btnCancel_Click;

          //btnComment.Text = "Write Comment";
      }

       protected void btnCancel_Click(object sender,EventArgs e)
        {

            PlComment.Visible = false;
            btnComment.Visible = true;
        }

What I have tried:

I have tried using FindControl() method but could not get it.
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Panel p = (Panel)dlAnswers.FindControl("PlComment");
p.Controls.Add(txtAnswerComment);
p.Controls.Add(btnSubmit);
p.Controls.Add(btnCancel);