Error using MPTCP

[alitalpur99]

Hello,
I wanted to run MPTCP on my Virtual box with Ubuntu 14.04 & MPTCP kernel 3.18.20-90-mptcp, Mininet ver 2.2.1.
I always get the following error after running the script mptcp_2hNs.py

python mptcp_2hNs.py --bw 10 --mptcp -n 2
*** Creating network
*** Adding controller
*** Adding hosts:
h1 h2
*** Adding switches:
s1 s2
*** Adding links:
(10.00Mbit) (10.00Mbit) (h1, s1) (10.00Mbit) (10.00Mbit) (h1, s2) (10.00Mbit) (10.00Mbit) (h2, s1) (10.00Mbit) (10.00Mbit) (h2, s2)
*** Configuring hosts
h1 h2
setting MPTCP enabled to 1
setting MPTCP ports to 1
Traceback (most recent call last):
File "mptcp_2hNs.py", line 170, in
main()
File "mptcp_2hNs.py", line 166, in main
genericTest(args, topo, setup, run, end)
File "mptcp_2hNs.py", line 148, in genericTest
setup(args)
File "mptcp_2hNs.py", line 97, in setup
set_mptcp_ports(args.ports)
File "mptcp_2hNs.py", line 53, in set_mptcp_ports
sysctl_set("net.mptcp.mptcp_ports", ports)
File "mptcp_2hNs.py", line 38, in sysctl_set
(stdout, stdout_expected))
Exception: Popen returned unexpected stdout: != net.mptcp.mptcp_ports = 1

My ifconfig results as below:
ifconfig
eth0 Link encap:Ethernet HWaddr 08:00:27:37:04:36
inet addr:10.0.2.15 Bcast:10.0.2.255 Mask:255.255.255.0
inet6 addr: fe80::a00:27ff:fe37:436/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:2429 errors:0 dropped:0 overruns:0 frame:0
TX packets:2187 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:869208 (869.2 KB) TX bytes:422795 (422.7 KB)

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:629 errors:0 dropped:0 overruns:0 frame:0
TX packets:629 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:74799 (74.7 KB) TX bytes:74799 (74.7 KB)