selecting from table I imported

Hi, I imported an excel file. When I select any field that is nvarchar it come back as invalid identifier. The fields that are datetime work fine though. Any ideas?

Thanks.

Hi,

can you please provide little bit more information? I need to know what type of DB are you using and would be great if you can give me some sample of data from your excel sheet which are you using so I can try it locally and identify problem.

Thanks