Declare the scalar variable error

See more:

C#

ASP.NET

Here is my code:

if (chkUpdate.Checked)
               {
                   string strID = GridView1.Rows[i].Cells[1].Text;
                 string v_item_no = GridView1.Rows[i].Cells[4].Text;
                   string strName = ((TextBox)GridView1.Rows[i].FindControl("txtName")).Text;
                   string strLocation = ((TextBox)GridView1.Rows[i].FindControl("txtLocation")).Text;

try
                 {
                     const string strUpdate = "Update gvtest set status ='Y' WHERE mem_id = @mem_id and item_no=@v_item_no";
                     cmd.CommandType = CommandType.Text;
                     cmd.CommandText = strUpdate.ToString();
                     cmd.Parameters.Clear();

cmd.Parameters.AddWithValue("@mem_id", strID);
                  cmd.Parameters.AddWithValue("@item_no", v_item_no);
                  cmd.Connection = con;
                  con.Open();
                  cmd.ExecuteNonQuery();
              }
              catch (SqlException ex)
              {
                  string errorMsg = "Error in Updation";
                  errorMsg += ex.Message;
                  throw new Exception(errorMsg);
              }
              finally
              {
                  con.Close();
              }

Message:

Error in updation. Must declare the scalar variable "@v_item_no"

Can anyone identify the error and help?