While importing from an excel spreadsheet i had only partial import of the contacts from the spreadsheet. after several attempts i discovered the cause was corrupted data on the spreadsheet. specifilly, the contacts had originally been entered into the sheet in the following format Last Name, First name. my assistant reformatted by creating a first name column and a last name column. but with a few of the names failed to delete the "Coma" that was at the end of the LAST NAME. when the comas were removed it imported fully and correctly.
Given as advice for others having problems importing data from excel.