[Solved] Update in RadGrid have Properties AutoGenerateColumns="true"

[Mr]

hi everybody
i am working with radgrid. i using property AutoGenerateColumns="true" and Set DataSource for radgrid
and i have Event

protected void RadUpdateResource_ItemDataBound(object sender, GridItemEventArgs e)
            {
                if (e.Item is GridEditableItem && e.Item.IsInEditMode)
                {
                    GridEditableItem dataItem = e.Item as GridEditableItem;
                    foreach (DataRow row in dsUser.Tables[0].Rows)
                    {
                        TextBox txtbx = (TextBox)dataItem[row["UserName"].ToString()].Controls[0];
                        txtbx.ID = row["UserName"].ToString();

                        if (txtbx.Text != "")
                        {
                            txtbx.Text = txtbx.Text.Remove(txtbx.Text.Length - 1);
                        }
                   }
               }
           }


and event for update for grid

 protected void RadUpdateResource_UpdateCommand(object source, GridCommandEventArgs e)
            {
                GridEditableItem editedItem = e.Item as GridEditableItem;
                int iActivityID = Convert.ToInt32(editedItem["ActivityID"].Text.ToString());

                foreach (DataRow row in dsUser.Tables[0].Rows)
                {
                    TextBox txtbox = (TextBox)editedItem[row["UserName"].ToString()].Controls[0];
                }
            }

but txtbox.Text alway is empty.
how i can get value for update

please help me
thanks

[Nguyen]

try

Protected void RadUpdateResource_UpdateCommand(object source, GridCommandEventArgs e)
            {
                GridEditableItem editedItem = e.Item as GridEditableItem;
                int iActivityID = Convert.ToInt32(editedItem["ActivityID"].Text.ToString());

                foreach (DataRow row in dsUser.Tables[0].Rows)
                {
                    TextBox txtbox = (TextBox)editedItem[row["UserName"].ToString()].FindControl(row["UserName"].ToString());
                }
            }

hope txtBox.Text!=""

thanks