I don't get it.
Only my wizard can hit it?
sometimes my halflinf rogue can hit it but thats rarely.
Most of the time it sais the weapon failed to hit the icorpeeral creature or something like that?
Is there a special way u have to hit it?
I think wraiths can only be hit by +1 weapons or better. even with those you sometimes fail to damage it. you just have to keep attcking it. also make sure you have some sort of restoration spell or potioin available in case it drains your consitution.