open/close position with multiple condition

Hi,

Can you please guide me coding in cAlgo with this case,I'm using sample RSI cbot.

i want open/close position when RSI line cross 30 or 70,

protected override void OnTick()
        {
            if (rsi.Result.LastValue > 30 || rsi.Result.LastValue > 70)
            {
                Close(TradeType.Sell);
                Open(TradeType.Buy);
            }
            else if (rsi.Result.LastValue < 70 || rsi.Result.LastValue < 30)
            {
                Close(TradeType.Buy);
                Open(TradeType.Sell);
            }
        }

and the problem is in backtest, when RSI line cross down 70 and open sell position but when it crossing up 70 again before reach level 30, its not close sell position or open buy position.

Did i miss something?

i'm sorry for my bad english,

Thanks in advance