hi, helpful folks

I am once again very confused, and would appreciate any help.  I am still trying to make a plot which contains frb's created from datafiles at different time steps.  This is what I have that I think should work, and doesn't:

from yt.mods import *
%matplotlib inline
import matplotlib.pyplot as plt
import matplotlib.colorbar as cb
from matplotlib.colors import LogNorm
import numpy as np

ts = TimeSeriesData.from_filenames("Strat_Box_hdf5_plt_cnt_01*")

print len(ts) #just checking
num = len(ts)

for index, val in enumerate(ts):
    print "%s = %s" % (index, val)  #again, just checking that this does what I think

orient = 'vertical'
fig, axes, colorbars = get_multi_plot( num, 1, colorbar=orient, bw = 6)

plots = []

for i, fn in enumerate(ts):
    pf = load(fn) # load data
    sl = pf.h.slice(0, pf.domain_center[0],fields=["Density","Temperature"] )
    frb = sl.to_frb( (1.0, 'kpc'), (4096,1024),height=(4.0, 'kpc'))
    dens_axes = [axes[0][i]]
    for ax in dens_axes:
        ax.xaxis.set_visible(False)
        ax.yaxis.set_visible(False)
    plots = [dens_axes[0].imshow(frb["Density"], origin='lower', norm=LogNorm())]

These are the errors that I get;

TypeError                                 Traceback (most recent call last)
<ipython-input-6-cd09eb0aaf88> in <module>()
      1 for i, fn in enumerate(ts):
----> 2     pf = load(fn) # load data
      3     sl = pf.h.slice(0, pf.domain_center[0],fields=["Density","Temperature"] )
      4     frb = sl.to_frb( (1.0, 'kpc'), (4096,1024),height=(4.0, 'kpc'))
      5     dens_axes = [axes[0][i]]

/Users/kde/yt-x86_64/src/yt-hg/yt/convenience.pyc in load(*args, **kwargs)
     65         try:
     66             from yt.data_objects.time_series import TimeSeriesData
---> 67             ts = TimeSeriesData.from_filenames(*args, **kwargs)
     68             return ts
     69         except YTOutputNotIdentified:

/Users/kde/yt-x86_64/src/yt-hg/yt/data_objects/time_series.pyc in from_filenames(cls, filenames, parallel, **kwargs)
    263                 filenames = glob.glob(filenames)
    264             filenames.sort()
--> 265         obj = cls(filenames[:], parallel = parallel, **kwargs)
    266         return obj
    267 

/Users/kde/yt-x86_64/src/yt-hg/yt/data_objects/static_output.pyc in __getitem__(self, key)
    146         for d in [self.units, self.time_units, self.parameters, \
    147                   self.conversion_factors]:
--> 148             if key in d: return d[key]
    149         raise KeyError(key)
    150 

TypeError: unhashable type