plot_date problem

Hello, I am having a problem with plot_date. I keep

    > getting the error:

    > Am I missing something obvious?

No, there is a bug in plot_date in setting the tick formatter object.
I didn't find this in any of my test or example scripts since all
those explicitly set the formatter and hence hid the bug. At the end
of the Axes.plot_date function in matplotlib.axes, replace

        self.xaxis.set_minor_locator(formatter)

with
        self.xaxis.set_major_formatter(formatter)

and you'll be good to go. Note however that there is a problem with
your script in that the length of your x and y arrays must be the
same. After making the changes above, try

from datetime import datetime
from matplotlib.dates import EpochConverter
from matplotlib.matlab import *

times = [1084195314, 1084195375, 1084195436, 1084195497, 1084195557]
vals = [10.2, 11.1, 8.7, 12.1, 12.2]
converter = EpochConverter()
ax = subplot(111)
plot_date(times, vals, converter)
savefig('test')
show()