Excel Import Identity Error

I am trying to import from an Excel Worksheet in the Enterprise Manager. I run through the wizard, and in transformations I have the Enable Identity Insert box checked, but when I run the import I get the following error:
Error at Destination for Row number 13880. Errors so far in this task: 1.
The statement has been terminated.
Cannot insert the value NULL into column 'ID', table 'CCReport.ITPSG.CCSPEND'; column does not allow nulls.
INSERT fails.

There are only 13881 rows, and I don't see anything in 13880 that is any different than the ones before it. Any ideas?try importing into the database first with out enabling the identity column, once it's imported then you can debug the data as well as re-populate the original table by doing any data manupulation.
" insert into originaltable
select columns from importedRawDatatable"