[CentOS] Help with custom udev rule

Hi,

I am trying create a custom udev rule to change the group and 
permissions on  /dev/net/tun.
Some research indicated that rather than directly editing the rule in 
/etc/udev/rules.d/50-udev.rules that I should create my own local rules 
file something like 10-local.rules  which contains
KERNEL=="tun", NAME="net/%k", OWNER="root", GROUP="vboxusers", MODE="0660"

But unfortunately when I reboot the permissions are still

0 crw------- 1 root root 10, 200 Oct 24 14:09 /dev/net/tun

Can anyone tell me what I'm doing wrong?  Or point me to some clear 
documentation about creating custom udev rules.

Thanks