Zealott is correct.. You have to at least put one training point into Each
Specialization Skill before you can get over 50 in one particular spec
skill.
I went into Alteration personally and just trained one point in all spec
skills and just my normal casting got ALT past 50 before any of the others
even got close. But if you are worried then you may just want to train in
the particular skill you want and wait until it is leveled up almost to 50
before training in the other skills.

Hope this helps,
Gallien
24 - Enc-Brell