Hi Everybody,
    I am trying to run this example from the cookbook

from yt.mods import *
from yt.analysis_modules.star_analysis.api import *
pf = load("data0030")
# Find all the haloes, and include star particles.
haloes = HaloFinder(pf, dm_only=False)
# Set up the spectrum builder.
spec = SpectrumBuilder(pf, bcdir="/home/user/bc", model="salpeter")
# Iterate over the haloes.
for halo in haloes:
    # Get the pertinent arrays.
    ct = halo["creation_time"]
    sm = halo["ParticleMassMsun"]
    metal = halo["metallicity_fraction"]
    # Select just the stars.
    stars = (ct > 0)
    ct = ct[stars]
    sm = sm[stars]
    metal = metal[stars]
    # Calculate the spectrum.
    spec.calculate_spectrum(star_mass=sm, star_creation_time=ct,
    star_metallicity_fraction=metal)
    # Write out the SED using the default flux normalization.
    spec.write_out_SED(name="halo%05d.out" % halo.id)

This is my code 

http://paste.yt-project.org/show/3885/

But I get this error:
Link length is 0.001000
Filling in 3697686 particles
Number of initial groups:6036
Number of groups:257
FOF CPU TIME: 10395.710700 secs
Found [ -1   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15  16  17
  18  19  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34  35
  36  37  38  39  40  41  42  43  44  45  46  47  48  49  50  51  52  53
  54  55  56  57  58  59  60  61  62  63  64  65  66  67  68  69  70  71
  72  73  74  75  76  77  78  79  80  81  82  83  84  85  86  87  88  89
  90  91  92  93  94  95  96  97  98  99 100 101 102 103 104 105 106 107
 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125
 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143
 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161
 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179
 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197
 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215
 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233
 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251
 252 253 254 255 256 257] unique groupings
yt : [INFO     ] 2013-09-25 15:15:27,721 Initializing HOP
yt : [INFO     ] 2013-09-25 15:15:27,721 Getting particle_position_x using ParticleIO
yt : [INFO     ] 2013-09-25 15:21:16,316 Getting particle_position_y using ParticleIO
yt : [INFO     ] 2013-09-25 15:25:36,923 Getting particle_position_z using ParticleIO
yt : [INFO     ] 2013-09-25 15:29:48,316 Getting ParticleMassMsun using ParticleIO
Copying arrays for 47944939 particles
Calling hop... 47944939 1.600e+02
nSmooth = 65 kd->nActive = 47944939
Building Tree...
Finding Densities...
Finding Densest Neighbors...
Grouping...
Merging Groups...
Writing Output...
All Done!Calling regroup...
No minimum group size specified.  Assuming 10 particles.
ngroups = 262744
yt : [INFO     ] 2013-09-25 15:52:17,649 Parsing outputs
yt : [INFO     ] 2013-09-25 15:52:24,347 Getting ParticleMassMsun using ParticleIO
yt : [INFO     ] 2013-09-25 15:57:00,506 Getting particle_position_x using ParticleIO
yt : [INFO     ] 2013-09-25 16:01:14,743 Getting particle_position_y using ParticleIO
yt : [INFO     ] 2013-09-25 16:06:14,673 Getting particle_position_z using ParticleIO
Traceback (most recent call last):
  File "StarsParticleAnalysys.py", line 48, in <module>
    spec = SpectrumBuilder(data_source, bcdir="/astro/py/", model="salpeter")
  File "/astro/yt-dev/yt-x86_64/src/yt-hg/yt/analysis_modules/star_analysis/sfr_spectrum.py", line 278, in __init__
    (100.0 * self._pf.hubble_constant),
AttributeError: 'AMRRegion' object has no attribute 'hubble_constant'

Any suggestion?
Thanks a lot in Advance!