Let me mention this, if you dont see cryo grenade in your arsenal, i would recommend going back to your class trainer. On the bottom of the training window there are some tabs, one for trooper, AND one for Commando( i think this is what it is named). from how you are describing this, it would seem like you haven't trained all of your AC skills from the trainer. I was lucky and had one of my brothers who plays on the same server mention to me when i was like lvl 13, to check the other tabs from the trainer, i didnt even think to for AC skills to train, i thought it was all in 1 place, but there is an AC specific tab you need to look at to see if you need to train those skills as well.