Can't buy skill

[Yorun]

Hello,

I've tried to purchase the Fire Bolt-skill 3 times now (twice from the Ruby and once from the guard in the Forest of Mist), but it doesn't show in my inventory nor in my Skill list.

Please help me out, if possible. T_T

(Note: My character's name is the same as the one I'm using to post here; Yorun)

Thanks in advance!