这个是什么东东啊郁闷

这个是什么错误啊郁闷
public int AddTitle(int classid, string title, string text, string photo)
  {
  StringBuilder strSql = new StringBuilder();
  SqlCommand cmd = new SqlCommand();
  SqlParameter pclassid = new SqlParameter("@vclassid", SqlDbType.Int, 4);
  SqlParameter ptitle = new SqlParameter("@vtitle", SqlDbType.NVarChar, 100);
  SqlParameter ptext = new SqlParameter("@vtext", SqlDbType.NVarChar, 8000);
  SqlParameter pphoto = new SqlParameter("@vphoto", SqlDbType.NVarChar, 50);
  pclassid.Value=vclassid;
  ptitle.Value = vtitle;
  ptext.Value = vtext;
  pphoto.Value = vphoto;

  cmd.Parameters.Add(pclassid);
  cmd.Parameters.Add(ptitle);
  cmd.Parameters.Add(ptext);
  cmd.Parameters.Add(pphoto);
   
  SqlConnection con = DB.con();
  int nResult = -1;
  try
  {
  strSql.Append(addtitle);
  con.Open();
  cmd.Connection = con;
  cmd.CommandType = CommandType.Text;
  cmd.CommandText = strSql.ToString();
  nResult = cmd.ExecuteNonQuery();
  cmd.Parameters.Clear();
  }
  catch (SqlException ex)
  {
  throw new Exception(ex.Message, ex);

  }
  finally
  {
  con.Close();
  }
  return nResult;
  }

老说这一句 ：nResult = cmd.ExecuteNonQuery();
字符串格式不正确 大家帮我看看吧 谢谢了
我是这样用的 
  protected void Button1_Click(object sender, EventArgs e)
  {
  int adclass = Convert.ToInt32(classid.SelectedValue);
  string adtitle = title.Text;
  string adphoto = photo.Text;
  string adtext = FCKeditor1.Value;
  //string project = project;
  Title addtitle = new Title();
  addtitle.AddTitle(adclass, adtitle, adtext, adphoto);
  Response.Write("添加成功");
  Response.Write(adtitle+"<br>"+adclass+"<br>"+adphoto+"<br>"+adtext+"<br>");

  }

[解决办法]
ExecuteNonQuery(); 
缺少参数
[解决办法]

C# code

nResult = cmd.ExecuteNonQuery();
[解决办法]
没看到你的SQL语句阿？
strSql="insert into.....";
加一条SQL语句看看