LTM 12 Radius load balancing datagram lb

I set up a virtual server to balance radius authentications using a custom Irule to have calling station Id as persistence attribute by uie. I kept datagram lb disabled as suggested by all deployment guides when clients use mschapv2. Nothing worked as long I kept datagram lb disabled, as soon as I enabled it maschapv2 authentication began to work. Unfortunately all the guides I read refer to bigip version 11. Is there something new in version 12? Please note that on our environment there is not source Nat of the clients. Thanks Marco