Python输出报错，看不出错误，不知道怎么搞

[待解决问题]

f = open('test.txt')

boy = []
girl = []
count =1

for each_line in f:
if each_line[:6]!='======':
(role,line_spoken)=each_line.split(':',2 )
if role =='小甲鱼':
boy.append(line_spoken)
if role =='小客服':
girl.append(line_spoken)
else:
file_name_boy='boy_'+str(count)+'.txt'
file_name_girl='gril_'+str(count)+'.txt'

  boy_file=open(file_name_boy,'w')
  girl_file=open(file_name_girl,'w')   
  
  boy_file.writelines(boy)  
  girl_file.writelines(girl)
  
  boy_file.close()
  girl_file.close()
  
  boy=[]
  girl=[]
  count +=1

f.close()

怎么会有下面输出的错误

Traceback (most recent call last):
File "C:/Users/Administrator/Desktop/python小程序/123.py", line 9, in <module>
(role,line_spoken)=each_line.split(':',2 )
ValueError: not enough values to unpack (expected 2, got 1)
[来自 Cnblogs For Xamarin]

python