If an order exists , even if there is a situation that satisfies my strategy later, another order cannot be opened.

For example,

IHistory history = context.getHistory();
double firstHistoryBarClosePrice = history.getBar(myInstrument, myPeriod, OfferSide.BID, 1).getClose();
double secondHistoryBarClosePrice = history.getBar(myInstrument, myPeriod, OfferSide.BID, 2).getClose();

if(firstHistoryBarClosePrice <secondHistoryBarClosePrice)
      engine.submitOrder(Label, selectedInstrument, IEngine.OrderCommand.BUY,tradeAmount, 0, slippage,  stoploss, takeprofit, 0, "");

if 2018.6.11 22:00,an order was submitted,and it's state is opened. Then at 23:00,a situation also can satisfy the strategy,but the engine won't submitt order.

There is only one order can exist.

Please help

It's impossible to create two orders with same label. Each order label must be unique.
If problem will not disappear, please provide full console log and i will try help you.

That's the full code,only one order can exist,another order can't open.Please help.

package examples;

import java.util.*;
import java.text.*;

import com.dukascopy.api.*;

public class example implements IStrategy {
    private IEngine engine;
    private IConsole console;
    private IHistory history;
    private IContext context;
    private IIndicators indicators;
    private IUserInterface userInterface;
  
 

    @Configurable("selectedInstrument:")
    public Instrument selectedInstrument = Instrument.EURUSD;
    @Configurable("tradeAmount:")
    public double tradeAmount = 0.0020;
    @Configurable("slippage:")
    public int slippage = 1;
    @Configurable("stopLossPips:")
    public int stopLossPips = 50;
    @Configurable("takeProfitPips:")
    public int takeProfitPips = 200;

    private static final DateFormat DATE_FORMAT = new SimpleDateFormat("yyyyMMdd_HHmmss");

    public void onStart(IContext context) throws JFException {
        this.engine = context.getEngine();
        this.console = context.getConsole();
        this.history = context.getHistory();
        this.context = context;
        this.indicators = context.getIndicators();
        this.userInterface = context.getUserInterface();

        context.setSubscribedInstruments(Collections.singleton(selectedInstrument), true);
    }

    public void onAccount(IAccount account) throws JFException {
    }

    public void onMessage(IMessage message) throws JFException {
    }

    public void onStop() throws JFException {
    }

    public void onTick(Instrument instrument, ITick tick) throws JFException {
        
        
        if (!instrument.equals(selectedInstrument)) {
            return;
        }

        if (!engine.getOrders(selectedInstrument).isEmpty()) {
            return;
        }
                                                   
        
    }

    public void onBar(Instrument instrument, Period period, IBar askBar, IBar bidBar) throws JFException
    {
        
        if (!instrument.equals(selectedInstrument)) {
            return;
        }

        if (!engine.getOrders(selectedInstrument).isEmpty()) {
            return;
        }
        
         if (!period.equals(Period.TEN_MINS)){ 
         return; 
         }
         
         long time = bidBar.getTime();
         
        double firstHistoryBarClosePrice = history.getBar(instrument, period.TEN_MINS, OfferSide.BID, 1).getClose();
        double secondHistoryBarClosePrice = history.getBar(instrument, period.TEN_MINS, OfferSide.BID, 2).getClose();
        
        
      
        
        if(firstHistoryBarClosePrice<secondHistoryBarClosePrice)
        {
            
            
            ITick lastTick = history.getLastTick(instrument);
            double sl = lastTick.getAsk() - instrument.getPipValue() * stopLossPips;
            double tp = lastTick.getAsk() + instrument.getPipValue() * takeProfitPips;

            engine.submitOrder(getLabel(time), selectedInstrument, IEngine.OrderCommand.BUY,tradeAmount, 0, slippage,  sl, tp, 0, "");     
             
          
            
        }
        
        
        
    }

    private String getLabel(long time) {
        return "IVF" + DATE_FORMAT.format(time) + generateRandom(10000) + generateRandom(10000);
    }

    private String generateRandom(int n) {
        int randomNumber = (int) (Math.random() * n);
        String answer = "" + randomNumber;
        if (answer.length() > 3) {
            answer = answer.substring(0, 4);
        }
        return answer;
    }
    

    
}

Thanks a lot!