帮忙下看看这代码哪里的问题

public DataSet DataSetUpdateByDataSet(DataSet ds, string strTblName)
        {
            SqlConnection conn = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\helperDB.mdf;Integrated Security=True;User Instance=True");
            SqlDataAdapter myAdapter = new SqlDataAdapter();
            SqlCommand myCommand = new SqlCommand(("select * from " + strTblName), (SqlConnection)conn);
            myAdapter.SelectCommand = myCommand;
            SqlCommandBuilder myCommandBuilder = new SqlCommandBuilder(myAdapter);
            try
            {
                myAdapter.Update(ds, strTblName);
            }
            catch (Exception err)
            {
                conn.Close();
                throw err;
            } return ds;
        }

strTblName传了个test

也就是和我数据库里面要更新的表一样，但是他报错了

Update 无法找到 TableMapping['test'] 或 DataTable“test”