why does only part of the excel file exported to outlook?

[WBR]

I've created an excel file (2003) with names and email address to export into
my Outlook 2003. After I go into Outlook; file: import/export and finish the
import I notice i am only importing half of my excel file names. Since, I
have seperated the remainder of names that did not import and now i get an
error message "An error has occurred in the Microsoft Excel translator while
getting the contents of a file system. The microsoft Excel file
"C:\..........xls" has no name ranges. Use Mucrosoft Excel to name the range
of data you want to import."

I can't seem to figure out how to fix this problem, please help.
Thanks
Wendy