Mininet-wifi Cannot import name OVSKernelAP with Python

Question

I am building a SDN network using Mininet-Wifi and I have this smallnetwork as a test just to learn more about Python, so I this code to run

!/usr/bin/python

from mininet.net import Mininet
from mininet.node import Controller, RemoteController, OVSKernelAP
from mininet.link import TCLink
from mininet.cli import CLI
from mininet.log import setLogLevel

def topology():

"Create a network."
net = Mininet( controller=Controller, link=TCLink, accessPoint=OVSKernelAP )

print "*** Creating nodes"
h1 = net.addHost( 'h1', mac='00:00:00:00:00:01', ip='10.0.0.1/8' )
h2 = net.addHost( 'h2', mac='00:00:00:00:00:11', ip='10.0.1.1/8' )

sta1 = net.addStation( 'sta1', mac='00:00:00:00:00:02', ip='10.0.0.2/8', position='50,50,0' )
sta2 = net.addStation( 'sta2', mac='00:00:00:00:00:03', ip='10.0.0.3/8', position='40,50,0')
sta3 = net.addStation( 'sta3', mac='00:00:00:00:00:04', ip='10.0.0.4/8', position='20,50,0' )

ap1 = net.addAccessPoint( 'ap1', ssid= 'new-ssid', mode= 'g', channel= '5', 
position='25,50,0', range='35' )
ap2 = net.addAccessPoint( 'ap2', ssid= 'new-ssid', mode= 'g', channel= '5', 
position='75,50,0', range='35' )

c1 = net.addController( 'c1' )

s1 = net.addSwitch('s1')

#net.runAlternativeModule('../module/mac80211_hwsim.ko')

print "*** Configuring wifi nodes"
net.configureWifiNodes()

print "*** Associating and Creating links"

net.addLink(ap1, s1)
net.addLink(ap2, s1)
net.addLink(s1, c1)
#net.addLink(ap1, ap2)

net.addLink(s1, h1)
net.addLink(s1, h2)

net.addLink(ap1, sta1)
net.addLink(ap1, sta2)
net.addLink(ap1, sta3)

print "*** Starting network"
net.build()
c1.start()
ap1.start( [c1] )
ap2.start( [c1] )

"""uncomment to plot graph"""
net.plotGraph(max_x=100, max_y=100)

net.startMobility(startTime=0)
net.mobility(sta1, 'start', time=1, position='0.0,50.0,0.0')
net.mobility(sta1, 'stop', time=30, position='100.0,50.0,0.0')
net.stopMobility(stopTime=31)

print "*** Running CLI"
CLI( net )

print "*** Stopping network"
net.stop()

if __name__ == '__main__':
setLogLevel( 'info' )
topology()

And after runing "sudo mn --custom test.py" (My file name is test.py ) I get the error.

Caught Excepcion. Cleaning up... ImportError: cannot import name OVSKernelAP

What Can i do? I have mininet and mininet-wifi already installed.