I can't speak directly to issues with a file exported from Lotus Notes, but in general I would guess that the file is not quite in the right format. I would suggest that you first review the Wiki page called
Import and Export of Contacts. My experience has been that a file exported from Outlook just works, but files from other programs need to be "tweaked" a bit. The main thing is that you don't need every column that is shown on the Wiki page, and the information doesn't have to be in any specific order. However, you do need the first row to have column names that exactly match the ones in the Wiki.