I'm getting the following error, While trying to run my code below.

I would really appreciate any help. Though I have checked several things already. Since, I'm new to Python. I thought maybe I'm missing something serious.

Runtime exception: KeyError: Equity(24, symbol='AAPL', asset_name='APPLE INC', exchange='NASDAQ GLOBAL SELECT MARKET', start_date=Timestamp('1993-01-04 00:00:00+0000', tz='UTC'), end_date=Timestamp('2015-08-24 00:00:00+0000', tz='UTC'), first_traded=None)
Blockquote

import numpy as np  
import pandas as pd

def initialize(context):  
    set_universe(universe.DollarVolumeUniverse(97, 100))  
    global Stock_Trading_Signal  
    #Global variable for each stock (dictionary), +1 if long in that stock or -1 if short in that stock  
    Stock_Trading_Signal = {}  

    global Stock_Trading_Price  
    #Global variable for each stock (dictionary), Holding the trading price. To check when our target for that position is met.  
    Stock_Trading_Price = {}  
    schedule_function(Daily_Rebalance, date_rule = date_rules.every_day(), time_rule = time_rules.market_open())  
def Daily_Rebalance(context, data):  
    pass

def handle_data(context, data):  
    global Stock_Trading_Signal  
    global Stock_Trading_Price  
    Stop_Price = 0  
    #Stop Loss Price Variable

    for stock in data:  
        if data[stock].mavg(45) > 1.025* data[stock].mavg(9):  
        # If Long Moving average is higher than short moving average  
            Stop_Price = data[stock].price * (1.015)  
            order_target_percent(stock, -0.05, style=StopOrder(Stop_Price))  
            Stock_Trading_Signal[stock] = -1  
            # Global Dictionary Variable to identify either long (+1) or Short (-1) Position  
            Stock_Trading_Price[stock] = data[stock].price  
            # Global Dictionary Variable. Holding the trading price. Used later to exit this trade, when our target for this trade is met  

        if data[stock].mavg(9) > 1.025* data[stock].mavg(45):  
        # If Short Moving average is higher than Long moving average  
            Stop_Price = data[stock].price * (0.985)  
            order_target_percent(stock, 0.05, style=StopOrder(Stop_Price))  
            Stock_Trading_Signal[stock] = 1  
            # Global Dictionary Variable to identify either long (+1) or Short (-1) Position  
            Stock_Trading_Price[stock] = data[stock].price  
            # Global Dictionary Variable. Holding the trading price. Used later to exit this trade, when our target for this trade is met  

        if context.portfolio.positions[stock].amount != 0:  
        #If We re Holding a Position in the stock  
            if Stock_Trading_Signal[stock] < 0:  
            #If We are holding a Short Position  
                if data[stock].price < Stock_Trading_Price[stock]*0.0985:  
                #If our target (1.5%) is met  
                    order_target(stock,0)  
                    #Exit complete trading position for this stock  
            elif Stock_Trading_Signal[stock] > 0:  
            #If We are holding a Long Position  
                if data[stock].price > Stock_Trading_Price[stock]*1.015:  
                #If our target (1.5%) is met  
                    order_target(stock,0)  
                    #Exit complete trading position for this stock