Some problem with Monte Carlo Solver mcsolve()

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I have installed Anaconda in my PC, QuTiP 4.1 and upgrade NumPy into "1.12.1".But there is some problem when I use the order mcsolve() to solve an example 

In [1]: times = np.linspace(0.0, 10.0, 200)

In [2]: psi0 = tensor(fock(2, 0), fock(10, 5))

In [3]: a  = tensor(qeye(2), destroy(10))

In [4]: sm = tensor(destroy(2), qeye(10))

In [5]: co = np.sqrt(0.1)*sm

In [6]: H = 2 * np.pi * a.dag() * a + 2 * np.pi * sm.dag() * sm + 2* np.pi * 0.25 * (sm * a.dag() + sm.dag() * a) 

 

It will depict 

But replace the co operators by none, it work well.