Hi John,
The file you attached does appear to be correct at first glance. The cell that contains "Name " has an extra space after the text. Once I removed this extra space, I was able to import the file just fine. If there are two or more words in the field name, you may optionally leave out the space between them (e.g. both "Assigned To" and "AssignedTo" will be accepted). Spaces after the text, however, are not supported.