python keyerror

总是无法运行，显示以下错误，请各路大神出手帮忙下，谢谢！！！
Traceback (most recent call last):
File "C:\Users\lenovo\Desktop\0.py", line 13, in <module>
input_data = input_data.sort_values(by = 'contract',ascending = 1)
File "C:\Users\lenovo\AppData\Local\Programs\Python\Python37\lib\site-packages\pandas\core\frame.py", line 4719, in sort_values
k = self._get_label_or_level_values(by, axis=axis)
File "C:\Users\lenovo\AppData\Local\Programs\Python\Python37\lib\site-packages\pandas\core\generic.py", line 1706, in _get_label_or_level_values
raise KeyError(key)
KeyError: 'contract'




# -*- coding: gbk -*-
import pandas as pd


input_data = pd.read_csv('C:\\Users\\lenovo\\Desktop\\overall\\ru2017overall.csv',sep = '\t',engine='python')

usecols = ['tradedate','contract','closingprice-1','closingprice','highestprice','lowestprice','askPrice','bidPrice']

parse_dates = (['contract'])

pd.set_option('expand_frame_repr', False)

input_data = input_data.sort_values(by = 'contract',ascending = 1)

malist = [3,7]

for ma in malist:

input_data['MA_' + str(ma)] = input_data['closingprice'].rolling(ma).mean()

input_data.to_csv('C:\\Users\\lenovo\\Desktop\\2017rupro\\ma.csv',encoding='gbk',index=False,sep=None)


file = open('C:\\Users\\lenovo\\Desktop\\2017rupro\\feedback.csv', 'w')

for line in open('C:\\Users\\lenovo\\Desktop\\2017rupro\\ma.csv', 'r'):

if line.startswith('tradedate'):

continue

bidPrice = int(line.split(',')[8])

askPrice = int(line.split(',')[7])

if bidPrice == 0 or askPrice == 0:

continue

ma3 = str(line.split(',')[9])

ma7 = str(line.split(',')[10])


if ma3 > ma7:

file.writelines( 'Buy, 20, ' + str(bidPrice)+"\n")

elif ma3 < ma7:

file.writelines( 'Sell, 20, ' + str(askPrice)+"\n")

else:

file.writelines( 'Wait, 00, ' + str(askPrice)+"\n")

file.close()