ช่วยด้วยครับไม่สามารถ UPDATE ค่าใน windows form application

using System.Data.SqlClient; 

namespace WindowsFormsApplication4
{
    public partial class Form1 : Form
    {
        SqlConnection CN = new SqlConnection("Data Source=.;Initial Catalog=PROJECT-FERN;User ID=sa;Password=12345");

        
        public Form1()
        {
            InitializeComponent();
        }


        DataView DV;
        SqlDataAdapter DAProduct;

        private void ShowProduct()
        {
            if (DS.Tables.Contains("JoinProduct"))
                DS.Tables.Remove("JoinProduct");

            string SQL = "Select*from Product inner join Category on Product.ProCat = Category.ProCat";
            DAProduct = new SqlDataAdapter(SQL, CN);
            DAProduct.Fill(DS, "JoinProduct");
            DV = new DataView(DS.Tables["JoinProduct"]);
            dataGridView1.AutoGenerateColumns = false;
            dataGridView1.DataSource = DV;
        }

        SqlDataAdapter DACategory;

        private void ShowCategory()
        {
            String SQL = "Select*from Category";
            DACategory = new SqlDataAdapter(SQL,CN);
            DACategory.Fill(DS, "Cat");
            comboBox1.DataSource = DS.Tables["Cat"];
            comboBox1.DisplayMember = "CatName";
            comboBox1.ValueMember = "ProCat";
        }


        DataSet DS = new DataSet();
        SqlDataAdapter DA;  

        private void Form1_Load(object sender, EventArgs e)
        {
            CN.Open();
            string SQL = "Select * from Product";
            DA = new SqlDataAdapter(SQL,CN);
            SqlCommand CM = new SqlCommand(SQL,CN);
            DA.Fill(DS,"Pro");

            ShowProduct();
            ShowCategory();

            this.textBox3.Text = DateTime.Today.ToString("dd/MM/yyyy");
            this.textBox2.Text = Program.EmpName;
       
        }

        private void button1_Click(object sender, EventArgs e)
        {

            DataRow DR = DS.Tables["Pro"].NewRow();
            DR["ProID"] = textBox1.Text;
            DR["ProName"] = textBox2.Text;
            DR["ProCat"] = comboBox1.SelectedValue;
            DR["ProTime"] = textBox3.Text;
            if (radioButton1.Checked)
                DR["ProSta"] = "หมด";
            else
                DR["ProSta"] = "ไม่หมด";
            DS.Tables["Pro"].Rows.Add(DR);
            DA.Update(DS,"Pro");
            ShowProduct();
            ShowCategory();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            DataRow[] DR = DS.Tables["Pro"].Select("ProID="+ textBox1.Text);
            DR[0]["ProName"] = textBox2.Text;
            DR[0]["ProCat"] = comboBox1.SelectedValue;
            DR[0]["ProTime"] = textBox3.Text;
            if (radioButton1.Checked)
                DR[0]["ProSta"] = "หมด";
            else
                DR[0]["ProSta"] = "ไม่หมด";
        }

        int i = 0;

        private void dataGridView1_CellMouseClick(object sender, DataGridViewCellMouseEventArgs e)
        {
            i = e.RowIndex;
            if (i >= 0)
            {
                textBox1.Text = DV[i]["ProID"].ToString();
                textBox2.Text = DV[i]["ProName"].ToString();
                comboBox1.Text = DV[i]["ProCat"].ToString();
                textBox3.Text = DV[i]["ProTime"].ToString();
                if (DV[i]["ProSta"].ToString() == "หมด")
                    radioButton1.Checked = true;
                else
                    radioButton2.Checked = true;
            }
        }
    }
}