def CheckAndTrade(self):
        for symbol in self.stock_symbol_list:
            if self.previous_5_day_volumes[symbol].Count != self.lookback_period:
                continue

            avg_volume = sum(self.previous_5_day_volumes[symbol]) / self.lookback_period
            current_volume = self.Securities[symbol].Volume

            if (current_volume > self.volume_threshold * avg_volume
                and self.Securities[symbol].BidVolume > self.bid_ask_ratio_threshold * self.Securities[symbol].AskVolume
                and current_volume > self.min_daily_volume):
                
                if not self.Securities[symbol].Symbol in self.open_positions:
                    self.SetHoldings(symbol, 1.0 / len(self.stock_symbol_list))  # Equal weight for each position
                    self.open_positions[symbol] = self.Securities[symbol].Price
                    self.Debug(f"Buying {symbol} at {self.Securities[symbol].Price}")

Would someone please help with the below. Seems im missing something here. I keep running on this error. Thanks