The Schema.ini file should be in the same directory as the file to be imported. If you changed the structure of the file to be imported, the error message you get may be a little obscure in that instead of a Schema.ini file, an Import Specification is actually being used. If you do not find a Schema.ini file, look for a specification. To find the specification, go to the tables window and right-click then start a manual import text (.txt) procedure (or go to File|Get External Data|Import). Select Text files from "Files of type" field at the bottom and browse for your import file. The Import Text Wizard will open and you should see the "Advanced" button you said you couldn't find. Click the Advanced button and you should then see a button allowing you to select a specification.
But! If you changed the import file structure, it probably will require you the change more that just the Schema or specification. Most likely, a table will have to be revised to accomodate the change.
