Did you use the VIA app note to configure your certificate deployment? https://community.arubanetworks.com/t5/Validated-Reference-Design/Virtual-Intranet-Access-VIA/ta-p/155614
You should turn on authmgr debugging to find out what is going on:
config t
config t
logging security process authmgr level debugging
Above is ArubaOS 8 syntax. The ArubaOS 6.x syntax is similar.
You would try to authenticate and then type "show log security 50" to get a sense what is wrong.