Use pyplot functions and embedded Qt widget

Can I use pyplot functions (such as pyplot.plot, pyplot.pcolormesh) to plot in embedded Qt plot?
I have created the following class

class CDeltaHPlot(FigureCanvasQTAgg):
     def __init__(self, parent = None):
         self.figure = Figure()
         self.axes = self.figure.add_subplot(111)
         FigureCanvasQTAgg.__init__(self, self.figure)
         FigureCanvasQTAgg.setSizePolicy(self, QSizePolicy.Expanding,

     def plot(self):

But it throws the following exception:
  File "/opt/develop/lib/python3.4/site-packages/matplotlib-1.4.0-py3.4-linux-x8
6_64.egg/matplotlib/", line 806, in sca
     raise ValueError("Axes instance argument was not found in a figure.")
ValueError: Axes instance argument was not found in a figure.

Kind regards, Petr.