Have you done all of the "prequests" to get to this one? You can click on prequests on the link above to see if you did miss something.
If you complete the prequests, and you activated the Sun School Obelisk, then you should be able to train on those spells. But remember, just like back in Ravenwood, when we wanted to train on a spell, we had to take the spells "in order". We could not just jump ahead and pick the spells that we wanted. We had to take the lower level spells first.
Did you train on the previous, lower level, Sun School spells already? In case you need to check them, this link shows all of the Sun School spells. You can click on any highlighted items for more details.