Talk:Pokemon EV Training, IV Training and Pokemon Natures/@comment-68.145.156.113-20170328093751/@comment-33971231-20170328094757

This is what I think may have happened...

Your Diancie may have been already maxed out in Sp. Attack. Did you trade for Diancie? Maybe the trainer who owned the Diancie before you EV trained it for you.

ANOTHER GOOD REASON IS you could have already used up ALL of your EV points, meaning you cannot gain more than the 510 EV point limit.

If you wanna be safe and make sure that your Diancie has properly EV trained as much Sp. Attack as possible, use one or two Mini Stat Resets and then try using Iso_SpAttack again to see if your sp. attack rises. Good luck training Diancie!