使用pyqt4调试python2 matplotlib

Question

我使用python2.7开发了一个带有Qt4和Matplotlib的GUI。 它是可运行的但我无法调试它，因为出现以下错误：

ImportError: 
    Importing PyQt4 disabled by IPython, which has
    already imported an Incompatible QT Binding: pyside

我一走到第4行就出现错误（来自matplotlib.backends.backend_qt4agg ......）

import matplotlib
matplotlib.use('Qt4Agg')
matplotlib.rcParams['backend.qt4'] = 'PyQt4'
from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas
from matplotlib.backends.backend_qt4agg import NavigationToolbar2QT as NavigationToolbar
from matplotlib.figure import Figure

from PyQt4.QtCore import *
from PyQt4.QtGui import *

任何提示？