Problem with unicode

Hi,
when doing the insert using these
                    cmd = new SqlCommand("insert into dbo.ite_tab (...,area,...) values (...,@area,...)", conn);
                    ...
                    cmd.Parameters.Add("@area", SqlDbType.NVarChar).Value = area_ddl.SelectedItem.ToString();

I am getting this in the table column in the DB,
中?

while the relevant Dropdownlist is having

中国

inside. why?

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Many Thanks & Best Regards, Hua Min