(this was used from an item so maybe not the same casting the spell - Item is Pumpkin Fiber Boots)
When the spell is used on a corpse you get a message saying that its not a valid target.
When you use the spell just on the ground, i acts as the default NWN spell and creates a ghoul is CL is less then level 12. This summon acts the same as an animal companion or familiar - you can initiate the same conversations with them. You also can not enhance the undead using the necromancy system.