post-up in interfaces doesn't work

[Mojtaba <kernel@rp2.org>]

Hello
I have a brand new jessie setup in a KVM VPS.
The server is in OVH network which needs manual routing applied.
However the post-up and setting in the /etc/network/interfaces is not executed
This is my interfaces file

auto eth0
iface eth0 inet static
address         198.50.210.32
netmask         255.255.255.255
broadcast       198.50.210.32
#gateway                192.99.39.254
post-up route add 192.99.39.254 dev eth0
post-up route add default gw 192.99.39.254
post-down route del 192.99.39.254 dev eth0
post-down route del default gw 192.99.39.254

I've tried a simple 'echo working > /testfile.txt' line but the
post-up or pre-up is not executed
Is there anything I'm missing?

Thanks