Matplotlib - why is the line color of the line chart black?

I use Matplotlib to display a list of floats. If there is a 100 float on my list, the graph displays the correct colors. But if there is a float in the list of 785, then it shows only black color. Here is the code.

import numpy as np
import matplotlib.pyplot as plt
import Image

Consensus = []
Prediction = []
Final = []
for line in open('1.out').readlines():
    words = line.split()
    Consensus.append(float(words[10]))
    Prediction.append(int(words[11]))

for i,j in zip(Consensus,Prediction):
    Final.append(i*j)

max_score = 3
length = 785
ind = np.arange(length)    # the x locations for the groups
width = 1       # the width of the bars: can also be len(x) sequence

p1 = plt.bar(ind, Consensus, width, color='red')
p2 = plt.bar(ind, Final, width, color='blue')

plt.ylabel('Scores')
plt.title('Scores by group and gender')
plt.xticks(np.arange(0,length,50))
plt.yticks(np.arange(0,max_score,0.2))
plt.savefig('testplot.png')
Image.open('testplot.png').save('testplot.jpg','JPEG')

This is an image of a program when the list is 785 in length.

This is when the list is 99 in length.

The file is available here - http://pastebin.com/HhPhgPDG

You can change only copy the first 100 lines of this file to check another case. You must change the length variable to the number of lines in the file.

Thank.