Button click event not firing and giving error
<p>I need guidance regarding my code.</p>

<pre><code> public class FacultyTemplatedynamic:ITemplate
{
    ListItemType ItemType;
    string FieldName;
    string InfoType;
    private bool isEditMode = false;
    protected bool isInEditMode
    {
        get { return this.isEditMode; }
        set { this.isEditMode = value; }
    }
    public FacultyTemplatedynamic(ListItemType itemType, string field_name, string info_type)
    {
        FieldName = field_name;
        ItemType = itemType;
        InfoType = info_type;
    }

    public void InstantiateIn(Control container)
    {
        switch (ItemType)
        {
            case ListItemType.Header:
                Literal header_litrl = new Literal();
                header_litrl.Text = "&lt;b&gt;" + FieldName + "&lt;/b&gt;";
                container.Controls.Add(header_litrl);
                break;
            case ListItemType.Item:
                switch (InfoType)
                {
                    case "Command":
                        ImageButton edit_button = new ImageButton();
                        edit_button.ID = "edit_button";
                        edit_button.ImageUrl = "~/Images/edit.gif";
                        edit_button.CommandName = "Edit";
                        edit_button.ToolTip = "Edit";
                        container.Controls.Add(edit_button);
                        break;
                    default:
                        Label field_lbl = new Label();
                        field_lbl.ID = "labelName";
                        //field_lbl.Visible =!(bool) isInEditMode;
                        field_lbl.Text = String.Empty; //we will bind it later through 'OnDataBinding' event
                        field_lbl.DataBinding += new EventHandler(OnDataBinding);
                        container.Controls.Add(field_lbl);
                        break;
                }
                break;
            case ListItemType.EditItem:
                if (InfoType == "Command")
                {
                    ImageButton update_button = new ImageButton();
                    update_button.ID = "update_button";
                    update_button.CommandName = "Update";
                    update_button.ImageUrl = "~/Images/update.gif";

                    update_button.ToolTip = "Update";
                    update_button.OnClientClick = "return confirm('Are you sure to update the record?')";
                    container.Controls.Add(update_button);

                    ImageButton cancel_button = new ImageButton();
                    cancel_button.ImageUrl = "~/Images/cancel.gif";
                    cancel_button.ID = "cancel_button";
                    cancel_button.CommandName = "Cancel";
                    cancel_button.ToolTip = "Cancel";
                    container.Controls.Add(cancel_button);

                }
                else// for other 'non-command' i.e. the key and non key fields, bind textboxes with corresponding field values
                {
                    Label field_lbl1 = new Label();
                    field_lbl1.ID = "LabelEdit";
                    //field_lbl1.Visible = (bool)isInEditMode;
                    field_lbl1.Text = String.Empty; //we will bind it later through 'OnDataBinding' event
                    field_lbl1.DataBinding += new EventHandler(OnDataBinding);
                    container.Controls.Add(field_lbl1);
                }
                break;
        }
    }

    private void OnDataBinding(object sender, EventArgs e)
    {
        object bound_value_obj = null;
        Control ctrl = (Control)sender;
        IDataItemContainer data_item_container = (IDataItemContainer)ctrl.NamingContainer;
        bound_value_obj = DataBinder.Eval(data_item_container.DataItem, FieldName);

        switch (ItemType)
        {
            case ListItemType.Item:
                Label field_ltrl = (Label)sender;
                field_ltrl.Text = bound_value_obj.ToString();

                break;
            case ListItemType.EditItem:
                TextBox field_txtbox = (TextBox)sender;
                field_txtbox.Text = bound_value_obj.ToString();

                break;
        }
    }
}




 private void CreateTemplatedGridView()
        {
            PopulateTable();
            for (int i = 0; i &lt; dt.Columns.Count; i++)
            {
                TemplateField tf = new TemplateField();
                tf.HeaderTemplate = new FacultyTemplatedynamic(ListItemType.Header, dt.Columns[i].ColumnName, dt.Columns[i].DataType.Name);
                tf.ItemTemplate = new FacultyTemplatedynamic(ListItemType.Item, dt.Columns[i].ColumnName, dt.Columns[i].DataType.Name);
                tf.EditItemTemplate = new FacultyTemplatedynamic(ListItemType.EditItem, dt.Columns[i].ColumnName, dt.Columns[i].DataType.Name);
                GrdMarkAttendance.Columns.Add(tf);
            }
            TemplateField tf1 = new TemplateField();
            GrdMarkAttendance.Columns.Add(tf1);
            GrdMarkAttendance.DataSource = dt;
            GrdMarkAttendance.DataBind();
        }

     private void PopulateTable()
        {
            dt = new DataTable();
            dt = obj.GetRegister();
        }    

     protected void GrdMarkAttendance_RowDataBound(object sender, GridViewRowEventArgs e)
        {
            PopulateTable();
            int i = dt.Columns.Count;          
            if (e.Row.RowType == DataControlRowType.DataRow)
            {

                DropDownList ddl = new DropDownList();
                ddl.ID = "ddl";
                ddl.Items.Insert(0, "Present");
                ddl.Items.Insert(1, "Absent");
                ddl.Items.Insert(2, "Leave");              
                e.Row.Cells[i].Controls.Add(ddl);
            }
        }    

    protected void Button1_Click(object sender, EventArgs e)
        {

        }  
</code></pre>

<p><strong>when I run this page and click on the button I got the following error:</strong> </p>

<p><em><strong>Server Error in '/' Application.</em></strong></p>

<p><em><strong>Multiple controls with the same ID 'labelName' were found. FindControl requires that controls have unique IDs.</em></strong></p>

<p><em>Description: An unhandled exception occurred during the execution of the current web</em> *request. Please review the stack trace for more information about the error and where it* *originated in the code. *</p>

<p><em>Exception Details: System.Web.HttpException: Multiple controls with the same ID</em> <strong>'labelName'</strong> <em>were found.</em> ** FindControl** <em>requires that controls have unique IDs.</em></p>

<p>*<strong>Source Error: *</strong></p>

<p><em>An unhandled exception was generated during the execution of the current web request.</em> *Information regarding the origin and location of the exception can be identified using *
<em>the exception stack trace below.</em></p>

<p>*<strong>Stack Trace: *</strong></p>

<pre><code>*[HttpException (0x80004005): Multiple controls with the same ID 'labelName' were found.* *FindControl requires that controls have unique IDs.]*
  *System.Web.UI.Control.FillNamedControlsTable(Control namingContainer, ControlCollection* *controls) +265*
  *System.Web.UI.Control.FillNamedControlsTable(Control namingContainer, ControlCollection*    * controls)* +311
   *System.Web.UI.Control.FindControl(String id, Int32 pathOffset) +145*
   *System.Web.UI.Control.FindControl(String id, Int32 pathOffset) +365*
   *System.Web.UI.Control.FindControl(String id, Int32 pathOffset) +365*
   *System.Web.UI.Control.FindControl(String id, Int32 pathOffset) +365*
   *System.Web.UI.Control.FindControl(String id, Int32 pathOffset) +365*
   *System.Web.UI.Page.FindControl(String id) +38*
   *System.Web.UI.Page.ProcessPostData(NameValueCollection postData, Boolean fBeforeLoad)*  +287 
   *System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean*  *includeStagesAfterAsyncPoint) +4911*  
</code></pre>

<ul>
<li><strong>I dont know why this error is coming yesterday it was wroking fine but when i use</strong> * 
<strong>FindControl in Row's particular cell</strong> <em>it started giving me error but now i remove *</em> <strong>that code and on click of button it was displaying the error.*   <em>Please give your *</em> **suggestions so that i can move further</strong></li>
</ul>

<p><strong>Sorry if i post question in wrong format or provide insufficient data</strong></p>
