Prevent cBot to send double order in a specific Symbol

Please help me to prevent cBot to send double order in a specific Symbol.

My code is like below which do not work.

if ((RSI.Result.LastValue > 50)  & (Positions.Where(x => x.SymbolName == Symbol.Name) == 0))
            {


                if (!IsPositionOpenByType(TradeType.Buy))
                {
                    OpenPosition(TradeType.Buy);
                }

                ClosePosition(TradeType.Sell);
            }

            if ((RSI.Result.LastValue < 50)   & (Positions.Where(x => x.SymbolName == Symbol.Name) == 0))
            {


                if (!IsPositionOpenByType(TradeType.Sell))
                {
                    OpenPosition(TradeType.Sell);
                }

                ClosePosition(TradeType.Buy);
            }