Why are you failing? Can you explain more?
Nevertheless, I would recommend using Red Gate
http://www.red-gate.com/products/sql-development/sql-developer-bundle/?source=products-a-page.
Mainly Red gate has multiple purposes, but there's a way to extract your schema without the data. Create a new empty database and try using SQL compare (that comes with the developer bundle of Red Gate) to compare the old db with the new empty one. It will allow you to generate a script that will create the tables for you with all their dependencies (foreign keys, constraints etc...)
Give it a shot, this the only thing that came to my mind now.