Why my backtesting program didn't enter any position?

Question

I am new to the field of programming, and recently I am trying to write a backtesting program by using backtrader. But it didn't enter into any position, can anyone tell me why?

CSV doc to run this program The csv doc is attached for your reference. For ['signal'] column, 1 = entry to long, 2 = entry to short.

I will be really appreciated it if anyone can give me a hand. QAQ

import backtrader as bt
import backtrader.analyzers as btay
import matplotlib
import backtrader.feeds as btf


class Supertrend(bt.Strategy):
    def __init___(self):
        signal = self.signal 
        tp = self.take_profit 
        sl = self.stop_loss 
        high = self.High
        low = self.Low
        
        if self.position: 
            temp = 0
    
    def next(self):
        if not self.position:
            if signal == 1: #做多
                temp = 1
                self.order = self.buy()
            elif signal == 2: #做空
                temp = 2
                self.order = self.sell()
        else:
            if temp == 1 and (high >= tp or low <=sl ):
                self.order = self.close()
            elif temp == 2 and (low <= tp or high >=sl ):
                self.order = self.close()

cerebro = bt.Cerebro()
cerebro.addstrategy(Supertrend)
  
data = bt.feeds.PandasData(dataname=df)
cerebro.adddata(data)
cerebro.broker.set_cash(8700)
cerebro.addsizer(bt.sizers.PercentSizer, percents = 50)
cerebro.broker.setcommission(commission=0.002)

print('Starting Portfolio Value : %0.2f' % cerebro.broker.getvalue())
cerebro.run()
cerebro.plot()

print('Final Portfolio Value : %0.2f' % cerebro.broker.getvalue())