Mana Problems

Hi everyone,
came back after a long break and made wizard instead of a warrior just to play something different.
I’m using the orb you get at the very beginning that consumes 80 mana. I’m at about level 70-80 and no matter to what offhand I change this orb, every time the secondary skill on my main hand becomes unusable. It says that I don’t have enough mana, which I do have enough.

not sure about the right number… it was few weeks ago dor me… but at level 70-80 u will need about 8-10k man to play with a comfort…
or find any Blood Magic set item… it will solve all your problems
and yeah… make sure you dont use any items with glasscannon affix… i guess i had the same problem in the past…
ps dont mix wizard ORB (spell) with wizard OH (offhand item)