Paladin Trainer and skill problem

It is wellknown that trainers keep in their list the spells already learnt. I think that this is the reason that i cannot train 2 of my skills (Seal of Light, Seal of Wisdom) to their next rank even though i have the lvl and previous rank requirments. Also the paladins Hammer of Wrath is not working. It is a spell that activates when the enemy 's hp is at 20% or lower. Just fix these thinks plz...