1) Whats its casting skill, until a certain skill it will have no spells to cast.
2) If its skill is low and all it has is dia for example, it can only cast dia 1x per 12 sec with the stormwalker frame/head, and thats only if dia isnt up.
3) What attachments do you have, i might be wrong but i thought stuff like scanner will actually stop you from casting certain spells if the targets magic resist > your pets magic acc, and if your pets magic skill is low, it might be preventing it from casting certain elemental nukes on the target.
4) In general make sure its stormwalker body + head (or whm/blm head). Make sure your auto has mp (equipment -> auto or /echo <petmpp>), from there just deploy it on something low level, kill it, then deploy it again. Once your skill starts getting to the 50+ range and you have a bunch of spells to cast you can move past easy areas.