How many records are in the found set?
In Page Setup, what printer is selected?
What color are the labels and fields set to?
What size are the labels and fields set to?
What font are the labels and fields set to?
If you create a new database with one field, one record, and some text in it, does it do the same thing?
A frequent way this can happen is when you have say 10 records in your current found set and your current record is not the first record. When you enter preview mode, it previews all 10 records, starting with page one of what will appear if you were to print with the current found set and printer setup options. If your first record in the found set has empty fields, you might get what you are describing here. WHen in preview mode, try clicking on the book control and see if you can advance to different pages and see if they have the data you are looking for.
If you want to preview just the current record, either sort your records so that it is the first record in your found set or omit all the other records so that it is the only record in the found set.