PolyCollection doesn't work - matplotlib

Question

I have a problem with PolyCollection matplotlib when I work with python 2.5. In random mode, it shows me following error: array dimensions must agree except for d_0 (file:collection.py - xy = np.concatenate([xy, np.zeros((1,2))])). This is my code:
from mpl_toolkits.mplot3d import Axes3D
from matplotlib.collections import PolyCollection
from matplotlib.colors import colorConverter
import matplotlib.pyplot as plt
import numpy as np
import matplotlib.font_manager as fm
from matplotlib.patches import Rectangle
import matplotlib.cm as cm
colors = ['#be1e2d',
'#666699',
'#92d5ea',
'#ee8310',
'#8d10ee',
'#5a3b16',
'#26a4ed',
'#f45a90',
'#e9e744']
row_names = ['2005','2006','2007']
data = [[1,1,1,1,1,1],[2,2,2,2,2,2],[4,4,4,4,4,4],[5,5,5,5,5,5],[7,7,7,7,7,7],[8,8,8,8,8,8]]
column_names = ['Ri','Pe']
#0 to start and end list
i=0
for i in range(len(data)):
data[i].append(0)
for i in range(len(data)):
data[i].insert(0,0)
dpi = 50.0
width = 460
height = 440
fig = plt.figure(1, figsize=(width/dpi,height/dpi),facecolor='w')
ax = fig.gca(projection='3d')#,azim=40, elev=0)
#Build axes
size = len(row_names) * len(data[0])
zs = np.arange(len(data))
# Setto le properties dei font
fp = fm.FontProperties()
fp.set_size('xx-small')
#Build Graph
verts = []
step = 1.0/len(data[0])
vertsColor = []
#Verify Single series or not
if len(column_names) > 1:
idx = 0
xs = np.arange(0, size, step)
change_color = len(column_names) - 1
for z in zs:
verts.append(zip(xs, data[z]))
vertsColor.append(colors[idx])
if idx == change_color:
idx = 0
else:
idx = idx + 1
################################################
# I THINK THE PROBLEM IS HERE
poly = PolyCollection(verts,facecolors=vertsColor)
ax.add_collection3d(poly, zs=zs, zdir='y')
################################################
ax.set_ylim3d(0, len(row_names)*len(column_names))
zs = np.arange(0,len(row_names) * len(column_names), len(column_names))
ax.set_yticks(zs)
lim = ((size*step)-step) - (len(row_names) - 1)
ax.set_xlim3d(0, lim)
rect = []
serie = []
#Build legend
for i in range(len(column_names)):
rect.insert(i,Rectangle((0,0), 1,1, facecolor=colors[i]))
serie.insert(i,column_names[i])
ax.legend((rect), (serie), loc=3, ncol=3, prop=fp)
else:
xs = np.arange(0, size, step)
for z in zs:
verts.append(zip(xs, data[z]))
poly = PolyCollection(verts,facecolors=colors) #[:len(data)])
poly.set_alpha(0.6)
ax.add_collection3d(poly, zs=zs, zdir='y')
ax.set_xlabel('Rec')
lim = ((size*step)-step) - (len(row_names) - 1)
ax.set_xlim3d(0, lim)
ax.set_yticks(zs)
ax.set_ylim3d(0, len(row_names))
#Find Max Value
max_value = 0
i=0
for i in data:
mass = max(i)
if mass > max_value:
max_value = mass
#Font Label X,Y,Z
for label in ax.get_xticklabels():
label.set_fontproperties(fp)
for label in ax.get_yticklabels():
label.set_fontproperties(fp)
for label in ax.get_zticklabels():
label.set_fontproperties(fp)
ax.set_xticklabels('')
ax.set_ylabel('Years')
ax.set_yticklabels(row_names, fontproperties = fp)
ax.set_zlabel('Values')
ax.set_zlim3d(0, max_value)
ax.set_title('Test',x=0.5, y=1)
plt.show()
THANKS.