C#对System.Data的数据类型及Oracle.DataAccess类型，问题

报错如下： 
Cannot convert type 'System.Data.Common.DbParameter' to 'Oracle.DataAccess.Client.OracleParameter'
对应源码：    /// 执行多条SQL语句，实现数据库事务。
        /// </summary>
        /// <param name="SQLStringList">多条SQL语句</param>  
        public static bool ExecuteSqlTran(string conStr, List<CommandInfo> cmdList)
        {
            using (OracleConnection conn = new OracleConnection(conStr))
            {
                conn.Open();
                OracleCommand cmd = new OracleCommand();
                cmd.Connection = conn;
                OracleTransaction tx = conn.BeginTransaction();
                cmd.Transaction = tx;
                try
                {
                    foreach (CommandInfo c in cmdList)
                    {
                        if (!String.IsNullOrEmpty(c.CommandText))
                        {
                            PrepareCommand(cmd, conn, tx, CommandType.Text, c.CommandText, (OracleParameter[])c.Parameters);    // 此行位置，扔出异常
                            if (c.EffentNextType == EffentNextType.WhenHaveContine || c.EffentNextType == EffentNextType.WhenNoHaveContine)
                            {
                                if (c.CommandText.ToLower().IndexOf("count(") == -1)
                                {
                                    tx.Rollback();
                                    throw new Exception("Oracle:违背要求" + c.CommandText + "必须符合select count(..的格式");
                                    //return false;
                                }                                object obj = cmd.ExecuteScalar();
                                bool isHave = false;
                                if (obj == null && obj == DBNull.Value)
                                {
                                    isHave = false;
                                }
                                isHave = Convert.ToInt32(obj) > 0;                                if (c.EffentNextType == EffentNextType.WhenHaveContine && !isHave)
                                {
                                    tx.Rollback();
                                    throw new Exception("Oracle:违背要求" + c.CommandText + "返回值必须大于0");
                                    //return false;
                                }
                                if (c.EffentNextType == EffentNextType.WhenNoHaveContine && isHave)
                                {
                                    tx.Rollback();
                                    throw new Exception("Oracle:违背要求" + c.CommandText + "返回值必须等于0");
                                    //eturn false;
                                }
                                continue;
                            }
                            int res = cmd.ExecuteNonQuery();
                            if (c.EffentNextType == EffentNextType.ExcuteEffectRows && res == 0)
                            {
                                tx.Rollback();
                                throw new Exception("Oracle:违背要求" + c.CommandText + "必须有影像行");
                                // return false;
                            }
                        }
                    }
                    tx.Commit();
                    return true;
                }
                catch (System.Data.OracleClient.OracleException E)
                {
                    tx.Rollback();
                    throw E;
                }
                finally
                {
                    if (conn.State != ConnectionState.Closed)
                    {
                        conn.Close();
                    }
                }
            }
        }