Error in creating table. (Newbie)

I am trying to build my first schema on Informix after just having battled installation. We're using Informix On-Line 5.x on SCO Unix. Use the Informix utility to load my .sql file containing definitions for the new database schema. The following table is the first in my sql file. No table or key exists that needs to be dropped at this point. It returns an error that I'm creating a duplicate key. I think that this means that putting the "NOT NULL UNIQUE" designation on my primary key field may be the culprit. Even if this is so, I'd like to be able to give all candidate keys the same designation on some of our more complex tables. So, two questions: 1. Is there some parameter that I could modify to make this legal? 2. If the "NOT NULL UNIQUE" is a problem, what about more than one in a definition? CREATE TABLE A_E( a_e_no CHAR(8) NOT NULL UNIQUE, descriptio CHAR(30)); CREATE UNIQUE INDEX A_E_NO ON A_E(a_e_no);