If your files is not recognised as a HansaWorld file then:
1. Make sure files are in UTF-8 formatting, which is the HansaWorld export format. Please confirm that the files are the right format by opening the file and finding "UTF-8" in files header.
2. Make sure the file contains any data at all.
3. Try to re-export the data from HansaWorld again and allow some time for the new file to be populated with data, because exporting big files (several megabytes) can cause the files to appear as empty while they are being populated by data.