Problem in Importing data from excel to sql server

I have excel file that has field named Purpose. Its max length is 400 character. I import this file to sql server database table. And also i change the purpose field in sql server database table with nvarchar 400. But when i run this job, it gave me error message:

Error at source for row number 1215. Errors encountereed so far in this task: 1.
Data for source column 18 ('Purpose') is too large for the specified buffer size.

What should i do so that i still can import the data from excel to sql server database?

Thanks for your help.I have far fewer problems when I take spreadsheets and put them in Access and then import them into sql server from access than I do just importing from excel.