It's probably the same as with all scrypt-jane coins, there is not yet a cpu miner that can use stratum. Well there is, but it needs two small changes in the cpu-miner.c.
https://bitcointalk.org/index.php?topic=250501.msg2666452#msg2666452

I won't do it, I want to see if the Vertcoin community is smart or not.
Nevermind, this is not scrypt-jane.