If you get a "Cannot see your target" error, install maps on the server. You can find the download on the
http://forums.nahunta.org.
If you get any other error, check your spells_us.txt file or your spells_new table in the DB depending on which you use. You can find the link to the spell editor in the GeorgeS forum.
Lastly, make sure you are using #cast #### and have the character flagged as a GM in the DB.