Can't Train Initial Skill Point - Disarm Trap

[Baron]

My rogue just hit level 16 and I tried to put the initial point into the disarm trap skill. For some reason it says I am already trained to the limit of my abilities in this skill.

I'm taking a wild guess here but is it because the sense trap skill has to be higher than the disarm trap skill and when you train them, both skills are the same level?

Any advice as to why it won't let me train it?