Nostalrius Begins - Quality wow vanilla realm (1.12)

After one battle, and sometimes during one battle, my mana is drained. Is this something locks have all the time or has it something to do with my build? I'm full destro and half affli.

http://db.vanillagaming.org/?talent#IV0ihobZZex0tM0tt

SillySingu wrote:'m full destro and half affli.

Found the issue.
Go read the warlock guide, it has a good leveling spec.