Children order in Bracket Order can no be executed in the day

uaotrly

I have a question about the execution of the children order (the take profit order) in a bracket order.

Each day, I place a parent order to buy at 74.70 and its child to take profit at 75.18.

At 2020-02-03, the buy order (74.70) is successfully executed during the day. Then the day is closed at 76.26, which means the price has certainly go through the take-profit order's price (at 75.18) before the day is closed. However, it has not been executed.

Here is the log:

2020-01-31, Open: 79.29, High:  79.72, Low:  76.17, Close: 76.47
2020-02-03, ORDER Accepted, Price: 74.70, isbuy True
2020-02-03, ORDER Accepted, Price: 75.18, isbuy False
2020-02-03, BUY EXECUTED, Price: 74.70, Cost: 747.00, Comm 0.75
2020-02-03, Open: 75.18, High:  77.45, Low:  74.67, Close: 76.26
2020-02-04, ORDER Accepted, Price: 74.70, isbuy True
2020-02-04, ORDER Accepted, Price: 75.18, isbuy False
2020-02-04, SELL EXECUTED, Price: 77.90, Cost: 747.00, Comm 0.78
2020-02-04, OPERATION PROFIT, GROSS 32.00, NET 30.47
2020-02-04, Open: 77.90, High:  78.97, Low:  77.49, Close: 78.78
2020-02-04, (MA Period 20) Ending Value 10030.47

And the next() function in my strategy:

    def next(self):
        # Simply log the closing price of the series from the reference
        self.log('Open: %.2f, High:  %.2f, Low:  %.2f, Close: %.2f' % 
                 (self.dataopen[0], self.datahigh[0], self.datalow[0], self.dataclose[0]))
        self.define_orders_for_next_day()


    def stop(self):
        self.log('(MA Period %2d) Ending Value %.2f' %
                 (self.params.maperiod, self.broker.getvalue()), doprint=True)

    def define_orders_for_next_day(self):
        this_long = self.buy(price=74.70, 
                             exectype=bt.Order.Limit, transmit=False, size= 10)
        limit_long = self.sell(price=75.18, exectype=bt.Order.Limit,
                               transmit=True, parent=this_long, size= this_long.size)

Since the parent order has been executed, why the child order can not be executed even if its trigger price has been hit?
Thanks for your responses !